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Abstract

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Introduction

In the year 918, at the onset of the tenth century, Koryŏ was founded on the Korean Peninsula, while in mainland China the Song (宋) dynasty was established in 960, following the chaos of the Five Dynasties and Ten Kingdoms period. Located to the north of Song and Koryŏ, the Khitan (契丹; ch. Qidan; kr. Kŏran) Empire, also known as the Liao (遼) dynasty, rose as a great power in East Asia after overthrowing Parhae (渤海; ch. Bohai) in 926, while the Tangut people (党 項族) formed an independent force in the present-day Gansu (甘肅) region in northwest China, becoming a pivotal part of international relations. It is generally understood that during this time the Song dynasty, a Central Plains (中原) state, was in a weaker position compared to the Khitan empire or the Western Xia (西夏), founded by the Tangut people, and therefore there was no de-facto tributary relationship centered around the emperor of the Central Plains (中原) and its surrounding states. This has led to suggestions and proposals that this time period needs to be examined with a pluralistic approach. One of the approaches to understanding this time is through attempts to interpret the relationships among nations, centered around the Khitan empire, striving to establish a balance of power as a “triangular relationship.”

The triangular relationship frame examines the international situation with a bipolar power distribution between the Khitan and the Song, which wielded the greatest influence on surrounding countries at the time, and Koryŏ and Western Xia as the third variables. This frame may be useful for understanding the relationships among specific states within a given time frame, but it may be lacking to explain the complex interests of the various states involved, considering that even the Song dynasty, which wielded a great power at the time, was merely one of the several powerful states of the time, as can be inferred from the expression “China among equals.”¹ In other words, we cannot be certain that discussing international relations during the 10th through 12th centuries through a bipolar system, while ignoring the relationships among several equal powers would be helpful for understanding the world order at the time. It is also important to point out that, at the time, there were various pre-state polities, such as the Jurchen (女 眞) and the Zubu (阻卜), that also had an impact on the world order, yet their importance have not been examined in detail. Therefore, this study aims to examine the formation of the balance of power system among various states and political forces in East Asia from the 10th century to the 12th century, and gain insights into the Koryŏ-Khitan relations at the time through this process.

International Relations and the Balance of Power

Understanding the characteristics of the Koryŏ-Khitan relations requires an understanding of the two states’ roles in the international community. It is clear that at the time the bilateral relations were led by the Khitan, and Koryŏ reacted accordingly. This trend is strongly relevant to Koryŏ’s geopolitical location at the time.

Xu Jing 徐兢 (1091–1153), who visited Koryŏ as a Song envoy in 1123 (first year in the reign of Great King^2, Injong of Koryŏ), described in Gaoli tujing 高麗圖經 (kr. Koryŏ togyŏng, Illustrated accounts of Koryŏ) that Koryŏ was cut off by the Liao Sea 遼海 to the south, by the Liao River 遼水 to the west, by the ancient land of the Khitan to the north, and by the Jin 金 to the east.³ Though the account was written after the fall of the Khitan, Xu Jing mentioned that Koryŏ bordered by land the Khitan to the northwest and the Jurchen, which had not yet grown into a state, to the northeast. Considering that Koryŏ was bordered by the sea on three sides, it is surmisable that it would have been difficult for Koryŏ to trigger conflicts against the Khitan, which possessed a far superior military power.

The territory of the Khitan, which spanned Manchuria, Mongolia, and northeastern China, can be inferred from the description in the chapter “Baiguanzhi” 百官志 (Monograph on the state offices) in Liao shi 遼史 (History of the Liao Dynasty): “Liao borders Koryŏ to the east, faces six powerful dynasties of the Later Liang 梁, Later Tang 唐, Later Jin 晉, Later Han 漢, Later Zhou 周, and the Song to the south, and confronts more than a dozen great countries, such as the Zubu (also called Shubugu 朮不姑) to the north. To the west, it suppresses a hundred powerful nations, including Western Xia, Tangut, Tuyuhun 吐渾, and the Uyghur 回鶻. Occupying a region amidst continuous warfare, it crouches like a tiger, and no one dared confront it.”⁴

The Khitan bordered Koryŏ and various other states and political forces in all directions. Its geographical location enabled the Khitan to expand its territory in all directions at a time when its military prowess far outstripped that of its neighboring nations and “no one dared confront” the Khitan. However, when its military power was not as superior to that of other nations, it faced a high likelihood of allied attacks from its neighbors. Considering such situation, it would have been difficult for the Khitan to be involved in simultaneous military conflicts against several neighboring states. Meanwhile, it is likely that the states with weaker military powers aimed to maintain a sort of balance of power by forming a coalition to keep the Khitan in check. In international relations, the balance of power refers to a system in which two or more actors maintain an equal distribution of power. Realist international relations scholars believe that it is not only inevitable for the continued existence of nation-states and political systems consisting of nation-states to be ruled by the balance of power theory but also that the balance of power system may be the only way to achieve peace, albeit incomplete.

The attempt to maintain a balance of power during this time period can be perceived from “Hebei shouyu shi’er ce” 河北守禦十二策 (Twelve Defense Strategies for Hebei), petitioned by Fu Bi 富弼, the director of the Bureau of Military Affairs 樞密院使 in the Song dynasty under Emperor Renzong 仁宗 in 1044 (tenth year in the reign of Great King Chŏngjong of Koryŏ):

Fu Bi was well aware of the Khitan’s internal circumstances,^6, as he had visited the empire as a Song envoy, once in 1041^7, (tenth year in the Zhongxi 重熙 era) and twice in 1042.⁸ In describing the situation at the time, Fu Bi proposed the strategy of using a strong enemy to subdue another strong enemy as he believed that the Song would not be able to stop the Khitan if it decided to invade its southern neighbor. He explained that the Song was strong enough to subdue Western Xia, located to the west of the Song, but that the Song must join forces with other countries to prevent the Khitan, which was ten times stronger, from launching an attack. This petition shows that the Song’s military power was relatively weaker compared to the Khitan, which had subdued foreign powers, including Western Xia and Koryŏ, and therefore the Song was in a position to seek ways to maintain a balance of power in the region.

The Khitan, however, was also not in a position to fully overpower the Song, as it considered Five Dynasties and the Song dynasty, which were established in the Central Plains, formidable enemies unlike other states. This perspective is confirmed by Xiao Hanjianu 蕭韓家奴, a Khitan official, who mentioned that the Khitan’s great enemy was in the south⁹ in his explanation of the international situation to Xingzong Khan 興宗 in 1035 (fourth year in the Zhongxi era). The Khitan considered the Song its equal at the time, which can be seen from “Yifengxian Woruyuan beiji” 義豐縣臥如院碑記 (The Stele Inscription for Woru Monastery in Yifeng County), written in 1081.

A close look at the stele inscription, which was inscribed during the time of Daozong Khan of the Khitan, shows that Koryŏ, marked as the East Han, and Western Xia, located to the west of the Khitan, “offered local products and paid tributes,” illustrating that the Khitan had supremacy over these two states. On the other hand, it describes the Song as “Song of the south” and the Khitan as “Liao of the north,” placing the two states on an equal footing. Similar description can be also seen from the chapter “Binli”^11, 賓禮 (Ceremonies for Receiving Foreign Envoys) in Liao shi from the words: “Does the emperor of the Southern Dynasty receive ten thousand fortune?” 南朝皇帝聖躬萬福 and “envoys of the Southern Dynasty” 南朝國信使. The Khitan calling the Song the “Southern Dynasty” 南朝 is an admission that there was an equilibrium of power^12, between the Khitan and the Song, in which the Khitan could not fully overpower the Song. On the other hand, the chapter “Binli” in Liao shi includes parts where the Khitan monarch inquires after Koryŏ’s Hyŏnjong 顯宗 and Western Xia’s monarch by their names, saying, “How is Wang Sun”^13, 王詢安否 and “How is so-and-so?”¹⁴ 某安否. This shows that compared to the Song, Koryŏ and Western Xia were considered to be of a lower rank, which indicates a hierarchy in the international world order as recognized by the Khitan from the 10th to the 12th centuries.

In consideration of such situation at the time, some scholars have presented views in understanding the international relations of East Asia as being interlocked, with the Khitan and the Song were the two major axes and Koryŏ and Western Xia as the third axis. Although there are slight differences among the views presented, they have established triangular relationships of “Koryŏ-Song-Khitan” or “Western Xia-Song-Khitan,” while examining the relationship between the regions of the Central Plains and Manchuria from a macroscopic perspective. ^15, Such discussions are based on the perception that the Khitan was a clear threat to the neighboring states, but it did not completely outstrip their forces, meaning that ultimately the Khitan was also one of the pillars in the balance of power. As an extension of such discussions, there were also attempts to understand the international relations in East Asia at the time through a double triangular relationship( Song-Koryŏ-Khitan and Song-Khitan-Western Xia),^16, or multiple triangular relationships in addition to the Koryŏ-Song-Khitan and Western Xia-Song-Khitan relations, such as Song-Western Xia-Tubo 吐 藩 (Tibet), Ganzhou 甘州 (Uyghur Kingdom)-Kucha 龜玆-Tubo, Koryŏ-Song-Japan, Song-Jiaozhi 交趾-Champa 占城.¹⁷

These attempts to understand international relations through the framework of triangular relationships had positive impact in that they broadened the understanding of the complex international relations in the pre-modern era. However, it is questionable whether the triangular relationship framework can be used to gain an accurate understanding of the complex international relations involving several states that were considered to be equals in East Asia from the 10th through 12th centuries, as this framework premises that the Khitan and the Song were two superpowers in the region and aims to understand the history of the region through their confrontational or peaceful relations with a third state. As mentioned earlier, the Song and the Khitan were merely two of several states that were considered to be equals.

The triangular relationship framework posits the two states of the Khitan and the Song as two main pillars of the triangle. Although it is true that the two countries have achieved a balance of power, their relationship was not always confrontational. In Tuhua jianwen zhi 圖畵 見聞誌 [Record of experiences in painting], Guo Ruoxu 郭若虛 writes as follows:

This shows that the conflict between the emperor’s country, the Song, and the Khitan was not always ongoing. The two states signed a friendship treaty in 1004 (7th year in the reign of Great King Mokjong 穆宗 of Koryŏ). Although there may be differences in interpretations depending on the perspective, if we accept this record to be true, it seems evident that the two states enjoyed peaceful relations from then until about 1074. During that period, the Khitan waged a series of wars, against Koryŏ from 1010 to 1020, and against nomadic polities in the northwest, such as the Zubu, from 1026 to 1037.^19, Likewise, the Song was also engaged in armed conflicts with Western Xia from 1040 to 1042.²⁰ While the Song and the Khitan maintained peaceful relations, they each fought wars with other polities. There is no doubt that the Khitan and the Song were able to wage wars with states and polities other than each other because of the peaceful relations between themselves. This situation can be explained with the triangular relationship framework, as the Khitan established friendly relations with the Song and waged wars against Koryŏ, Zubu, and others, while the Song established friendly relations with the Khitan and waged wars against Western Xia.

The fact that the Khitan and the Song were not always in conflict is evident from the Khitan’s request for reinforcements to attack Koryŏ sometime between May 1301, when Koryŏ’s Great King Tŏkjong came to the throne, and 1033. Around this time, Koryŏ and the Khitan were clashing over the issue of returning the territory occupied by the Khitans in the region east of the Amnok (鴨綠; ch. Yalu) River. At the time, the Song was under the rule of Emperor Renzong 仁宗 (1022–1064), and Empress Mingsu 明肅太后 (970–1033), who had been ruling as a regent for over a decade, wanted to accept the Khitan’s request for reinforcements. However, the request was not granted due to objections from Lü Yijian 呂夷簡 (979–1044).^21, Such move to forge military alliance between the two states was possible because they were not in a confrontational relationship. Moreover, the fact that the Khitan requested reinforcements from the Song to attack Koryŏ in itself indicates the Khitan did not solidify its position as an “absolute power” in the region. This situation is also intimately related to the major defeat the Khitan suffered at the hands of Koryŏ in Kuiju 龜州 in 1019. Regarding the battle of Kwiju, Song official Fu Bi stated that the Khitans suffered such an utter defeat that they could not save a single horse or a cart to bring back home, and that afterward they dared not attack Koryŏ out of fear.^22, Upon witnessing this event, Ch’ŏlliguk 鐵利國 and other polities in the Manchurian region began to dispatch envoys to Koryŏ in an effort to improve relations with Koryŏ. This was a time when the leadership in the international relations had been shifted to Koryŏ.²³ Although it is unclear how long this period of Koryŏ’s leadership in lasted, the fact that it was in a leadership position attests to Koryŏ’s position as an important pillar of international relations in East Asia at the time, and furthermore suggests that to correctly understand the international situation at the time, it is necessary to break away from the conventional framework of considering the Song and the Khitan’s influence in the region as absolute.

There are other aspects of international situations that are difficult to explain through the conventional triangular relationships. One such aspect is the fact that the Khitan was the state that benefited the most from the aforementioned war between the Song and Western Xia from 1040 to 1042. The Khitans were reluctant to let the Western Xia become stronger.^24, It rejected Western Xia’s offer for the two of them 1to form alliance and attack the Song, and instead succeeded in receiving an additional 100,000 taels 兩 of silver and 100,000 bolts 匹 of silk in annual tributes from the Song than what had been agreed on in the Chanyuan Treaty 澶淵之盟. Western Xia grew aggravated when most of the profits went to the Khitan despite winning several battles against the Song. And when the Khitan ended up mediating negotiations between Western Xia and the Song, Western Xia started an armed conflict against the Khitan.²⁵ This shows that Western Xia was also a sovereign state that was neither subordinate to the Khitan nor the Song and, in fact, was not afraid to clash with them for its own interests.

In 1044, five tribes under the sphere of the Khitan’s influence, including the Tangut and the Southwest Pacification Inspector Luohannu 西南面招討都監 羅漢奴, betrayed the Khitan and allied themselves with Western Xia.^26, The Khitan attacked the Tangut to punish them. The Tangut requested reinforcements from Western Xia, and Western Xia in turn requested military assistance from the Zubu. The Zubu sided with the Khitan by capturing and sending to the Khitan the Western Xia envoy who came to ask the Zubu for help,^27, and what began as a war between Western Xia and the Song led to a war between Western Xia and the Khitan, with the Tangut supporting Western Xia and the Zubu siding with the Khitan. An interesting aspect in this conflict is that even the Song, which was in friendly relations with the Khitan, appointed Li Yuanhao 李元昊 as the monarch of Western Xia and promised^28, an annual grant²⁹ 歲賜 of 255,000 taels in an effort to instigate an all-out war between the Khitan and Western Xia. This shows that, in addition to the states that were directly involved in conflicts, even the Song, which maintained peaceful relations with the Khitan, was keeping up with the changes in international affairs and making efforts to turn the international situation to their advantage. Considering the complexity of the situation, with the nomadic tribes of the Tangut and the Zubu, as well as the Song in the south, intervening in the war between the Khitan and Western Xia, there are aspects that cannot be explained by simplifying the situation into a triangular relationship.

Presumably, a state that had a relatively inferior military power would not have confronted a hostile country and instead aim to establish friendly relations with certain states in an effort to secure its own safety, as can be seen in the case of the Song dynasty.

This record shows that the Song aimed to divide the Khitan’s military power by allying with Koryŏ, Gusiluo, Mingzhu, Miezang, and Heishui Jurchen. In an effort to conquer the Khitan, the Song attempted to ally itself with Chŏngan’guk 定安國 in the east^31, and even sought to subjugate the Khitan by inciting the Tangut in the west to start a conflict.^32, Although the Song was only successful in its effort to establish alliances with the Tubo, the Kingdom of Khotan 于闐, and the Jin dynasty, it sought alliances with various other states and polities, including Gaochang 高昌 Uyghur, Zubu, Jurchen, Tubo’s Panluozhi 潘羅支 and Gusiluo regimes, Khotan, and Japan.³³ The states that the Song sought alliance with varied with the changing international circumstances, since for the Song, all other states in the region were needed solely to check the Khitan. This suggests that examining the relationships among various states and polities, rather than insisting on the triangular relationship framework, would provide a more accurate understanding of the changes in the situation in East Asia at the time.

Moreover, in existing studies, the triangular relationship framework is lacking in providing an adequate explanation of the international situation in East Asia at the time, as it focuses on the analysis of state-level polities and hardly mentions or outright excludes powerful polities that did not reach the level of a state, such as the Jurchen and the Zubu. An examination of the aforementioned chapter “Baiguanzhi” in Liao shi shows that the pre-state nomadic polity of the Zubu (Shubugu) is sometimes described as a great country (大國), and the Uyghur as a strong country (强國). From this text, it seems evident that even though their roles cannot be comparable to those of Koryŏ, the Song, or Western Xia, these pre-state polities were not negligible in the balance of power and international relations in East Asia. In particular, the Zubu seemed to have played a rather large role in the region, according to Liao shi:

In 1035 (fourth year of the Zhengxi era), Xiao Hanjianu mentioned the Zubu along with Koryŏ as not having submitted to the Khitan in explaining the regional affairs surrounding the Khitan. It is estimated that the Zubu inhabited the northwest frontier of the present-day Gansu region, in the proximity of Western Xia, alongside the Tangut. They are presumed to be the same tribe as the Tatars 韃靼.³⁵ Although the Zubu was not bordered with the Koryŏ, its impact on the international situation at the time is well illustrated in the Koryŏ-Khitan relations. The fact that the Zubu plays an essential part in understanding the Koryŏ-Khitan relations can be seen from the Khitan’s attitude when it invaded Koryŏ during the reign of Great King Hyŏnjong of Koryŏ.

In April 1012, the Khitan demanded that Great King Hyŏnjong of Koryŏ pay a personal tribute visit (kr. ch’injo 親朝). When Koryŏ refused, the Khitan demanded that Koryŏ cede the six garrison settlements. Koryŏ refused this demand as well. Yet, the Khitan acted in a conciliatory manner rather than inciting a physical conflict, only sending Yelü Xingping 耶律行平 (kr. Yayul Haengp’yŏng) three times, in March and July 1012 and again in April 1015,^36, and Li Songmao 李松茂 (kr. Yi Songmu) twice, in September 1014 and 1015,^37, to demand the cession of the six garrison settlements. Since the Song and the Khitan had already signed a peace treaty in 1004, the Khitan did not need to be concerned about an ambush from the Song. Moreover, the Khitan sent Yelü Ning 耶律寧 as an envoy to the Song before launching an attack on Koryŏ to inform them of an impending war with Koryŏ.³⁸ As such, it is difficult to infer that the Khitan was reluctant to clash with Koryŏ because of its relationship with the Song. Yet, the Khitan did not respond with a military measure despite Koryŏ’s provocation, which suggests that there were variables other than the triangular relationship of Koryŏ, the Khitan, and the Song.

Regarding the Khitan’s attitude, it is noteworthy that the Khitan’s relations with polities in the northwest, such as the Zubu, had deteriorated. The chaotic turmoil in the Khitan’s northwestern region include the Grand Preceptor 太師 Alidi 阿里底 of the seven tribes launching a rebellion after killing Imperial Commissioner Baan and his family in November 1012 (first year of the Kaitai 開泰 era) and being captured and taken to the Khitan by the Zubu, which was under the Khitan’s sphere of influence; all tribes on the border rebelling against the Khitan^39,; and the tribes of Wugu 烏古 and Dilie 敵烈 rising in revolt against the Khitan in January 1013. The Khitan’s Right Pishi army chief 右皮室 詳穩 Yanshou 延壽 was ordered to lead his troops to subdue the rebels. When soldiers of the Tatar confederation 達旦國 besieged Zhenzhou 鎭州 in the Khitan empire, Huage 化哥 was dispatched in March of 1013 to suppress the Northwest Route 西北路.^40, Records indicate that the Wugu and Dilie tribes ceded the Khitan’s old land in July of the same year,^41, and that in the same month, the Tangut revolted on the day of Yiwei 乙未 (kr. Ŭlmi) while the Khitan fought the Zubu on the day of Yiyou 乙酉 (kr. Ŭryu).^42, This illustrates that the Khitan was continuously involved in armed conflicts with nomadic tribes. In an effort to subdue the Tangut rebels, the Khitan even requested cooperation from Western Xia,^43, which suggests that the Khitan felt a considerable burden from the armed conflict in the region. There are also records of the Khitan’s Shengzong Khan 聖宗 appointing Xiao Xiaomu as a punitive officer of the Northwestern Route 西北路招討使 in December of the same year,⁴⁴ and of the Wugu inciting a rebellion in April 1014 and the Dilie of the eight tribes inciting a rebellion in September. These are evidence that the Khitan clashed with various polities on the Northwestern route.

Since September 1014, there are no mentions of large-scale military campaigns taking place in the Khitan northwest, which suggests that the empire was experiencing a certain level of stability. Then, starting in January of 1015 (sixth year in the reign of Great King Hyŏnjong of Koryŏ), the Khitan began to attack Koryŏ again, as mentioned earlier. This indicates that the attack on Koryŏ was closely related to the situation in the Khitan’s northwestern region. All in all, these facts signify that, in order to underhand the Koryŏ-Khitan relations, it is necessary to take into consideration not only the Song but also various political entities that did not necessarily have diplomatic relations with Koryŏ but influenced the Khitan behind the scenes.

The same conclusion can be reached from a close look at the Khitan’s attitude when Koryŏ took a hard-line stance of severing diplomatic relations with the Khitan, from the reign of Great King Tŏkjong 德宗 to 1038 (fourth year in the reign of Great King Chŏngjong). In 1031, immediately after Great King Tŏkjong was enthroned, Koryŏ requested the return of the Koryŏ envoys detained in the Khitan as well as the demolition of the garrison and bridge built by the Khitan across the Amnok River. The Khitan rejected Koryŏ’s request, which prompted Koryŏ to suspend the dispatch of envoys for offering New Year’s felicitation (賀正使), continue the use of the era name of the previous Khitan monarch, Shengzong Khan, and refuse to acknowledge the accession of the current monarch Xingzong Khan 興宗. Furthermore, in January of 1032 (first year in the reign of Great King Tŏkjong), Koryŏ refused the Khitan envoys’ entry into Naewŏn Fortress 來遠城 and built fortresses in areas such as Sakju 朔州, Yŏnginjin 寧仁鎭, and P’ach’ŏn 波川 to prevent invasions by the Khitan. Koryŏ’s suspension of dispatching envoys to the Khitan and refusing the entry of the Khitan envoys meant a cease in diplomatic relations, yet the Khitan was unable to take a hardline stance and apply military pressure on Koryŏ because it was engaged in a war with the Zubu from March 1026 (sixth year in the Taiping 太平 era) to 1038 (third year in the reign of Great King Chŏngjong of Koryŏ). It was not until September 1038, when its war with the Zubu had ended, the Khitan sent a letter, demanding Koryŏ’s loyalty, and threatened Koryŏ by sending naval forces into the Amnok River.⁴⁵ These historical situations once again confirm that an understanding of the Koryŏ-Khitan relations require an examination of the role of the Song as well as the role of the Zubu, who did not share a border or had diplomatic relations with Koryŏ.

At a time the Khitan was in conflict against the Song, there were states and polities that wielded great power in East Asia. Western Xia attempted to disrupt the Southern-Northern dynasty system of the Khitan and the Song, referring to itself as the “Western Dynasty” 西朝 and aiming to divvy up the region into three.^46, Similarly, Koryŏ also had its own unique view of the world, calling the Khitan “Northern Dynasty”^47, and the Song “Western Dynasty”^48, or “Southern Dynasty.”⁴⁹ Furthermore, as previously mentioned, pre-state polities such as the Jurchen and the Zubu also built up their forces. In such ways, East Asia at the time was a multistate region. This suggests that the triangular relationship framework, with a bipolar system of the Khitan and the Song, is not always suitable for explaining the political situation of East Asia.

National Security and Changes in International Relations

The two most important concepts in international politics are “sovereignty” and “security,” which do not exist independently of each other. A state prioritizes national security to maintain its independence. The reason states achieve a balance of power is not for peace but to protect their independence. The same would have been true of East Asian states in the 10th through 12th centuries. The Khitan was constantly concerned about the possible alliance of Koryŏ and the Song, as having two forces clashing at its borders on both sides would not have been a great situation for the Khitan. Thus, the Khitan made efforts to eliminate threats by strengthening its relationships with the neighboring states and polities while preventing alliances among them. This can be seen in the Khitan’s pretext for invading Koryŏ during the reigns of great kings Sŏngjong and Hyŏnjong of Koryo. In the leap month of October in 9 93 (12th year in the reign of Great King Sŏng jong of Koryŏ), the Khitan invaded Koryŏ for the following reason:

As justification for invading Koryŏ, the Khitan cited that Koryŏ was encroaching on the former Koguryŏ territory and that Koryŏ had diplomatic relations the Song while it had no relations with the Khitan, even though Koryŏ and the Khitan shared a common border. In response, the Koryŏ diplomat Sŏ Hŭi 徐熙 blamed the Jurchen for occupying the land between the Khitan and Koryŏ, and negotiated a compromise, promising to build a fortress and secure a safe passage to the Khitan empire if the Khitan returned Koryŏ’s old territory.^51, Since it was true that the Jurchen were interposed between Koryŏ and the Khitan, the Khitan could not put the entire blame solely on Koryŏ, and Sŏ Hŭi’s logical response allowed Xiao Hengde to persuade the Khitan’s Shengzong Khan to reconcile with Koryŏ.⁵²

In 1010, the first year in the reign of Great King Hyŏnjong of Koryŏ, the Khitan once again launched an expedition against Koryŏ, and the pretext for the invasion was similar to the one they gave for their invasion during the reign of Great King Sŏngjong.

This record from the reign of Great King Munjong of Koryŏ on the Khitan’s letter of inquiry on wrongdoings in 1010 confirms that the Khitan was concerned about Koryŏ’s ties with the Jurchen to the east and the Song to the west. The Khitan’s consistent concern over the Koryŏ-Song relations can also be seen from the Koryŏ Minister Yu Ch’am’s visit to the Khitan as an envoy⁵⁴ in 1041 (seventh year in the reign of Chŏngjong, during which the Khitan’s regent of the eastern capital seemed envious as he inquired about Koryŏ sending envoys to the Song. The Khitan seems to have considered an alliance between Koryŏ and the Song to be a great threat to its existence. This proves the necessity to take the Koryŏ-Khitan-Song relations into consideration to gain an accurate understanding of the Koryŏ-Khitan relations.

Although Koryŏ and the Song did not share a border, the two states shared a common goal of suppressing the Khitan. As a result, the Koryŏ-Song bilateral relations are understood to have been friendly. That, however, was not always the case and depended on the situation. In 986 (fourth year in the reign of Sŏngjong of Koryŏ), the Khitan attacked the Jurchen via Koryŏ territory, the Jurchen made a false accusation against Koryŏ to the Song, claiming that Koryŏ allied with the Khitan to capture the Jurchen people. Song Emperor Taizong ordered the Koryŏ envoy Han Suryŏng 韓遂齡 to free the Jurchen captives, and Great King Sŏngjong of Koryŏ worried and feared the Song’s attitude. ^55, The Song’s response must have been harsh, considering it instilled fear in Sŏngjong, and such response seems to have been a result of the Song’s concern over Koryŏ-Khitan alliance. In the same year, the Song sent Han Guohua 韓國華 to Koryŏ and requested military support to attack the Khitan, but Koryŏ stalled the dispatch of troops, at which point Han Guohua threatened the Koryŏ monarch: “If you do not make an effort, the Son of Heaven would be angered and lead a large army to the east and cut down those who do not obey his order. It would be similar to pouring seawater on a torch. If that happens, would Your Majesty have no regrets?”^56, Only after receiving a promise of troops from Koryŏ, Han returned to the Song.^57, This exchange between Han Guohua and the Koryŏ monarch about the possibility of the Song sending troops to Koryŏ reveals that the Koryŏ-Song relations were not always friendly.⁵⁸ Regarding this point, let us examine a record in Xu zizhi tongjian changbian 續資治通鑑長編 (The Long Draft of the Continuation of the Comprehensive Mirror for Aid in Governance), which chronicles the history of the Song:

When the Khitan launched an expedition against Koryŏ in 1010, the Song discussed its response in case Koryŏ enlisted military aid, ultimately deciding to reject Koryŏ’s request based on the fact that Koryŏ has not sent tributes for years. This, however, was only a pretext and illustrates that the Song’s priority was its own safety by maintaining friendly relations with the Khitan. This conversation between the Song Emperor Zhenzong and Wang Dan also hints at the Song’s desire to sustain amicable relations with the Khitan rather than enter into a conflict. This means that gaining an accurate understanding of reality at the time may be difficult if the Song and the Khitan’s relations are seen only as antagonistic. Even between the Song and Koryŏ, with whom the Song seemed to have maintained friendly relations, no military assistance was provided for each other between the two states, which indicates that the Koryŏ-Song relations were only specious.⁶⁰ This is supported by a statement made by Su Zhe 蘇轍 to Emperor Zhezong 哲宗 of Song:

Mentioning that there were no substantial benefits for either Koryŏ or the Song in their relations, Su Zhe explained that the reason the Song initiated exchange with Koryŏ through merchants in the Xining era (1068–1077), which was during the reign of Great King Munjong of Koryŏ), was to receive military assistance from Koryŏ in its troubles with the Khitan. This is a clear indication that the Song’s need for Koryŏ was to keep the Khitan in check. The same was true for Koryŏ, regarding its relations with the Song. In 1058 (12th year in the reign of Munjong), Munjong’s attempt to initiate diplomatic ties with the Song was met with objection from the Supreme Council 內史門下省, who asserted that doing so would likely sour Koryŏ’s currently peaceful relationship with the North Dynasty, meaning the Khitan, and there was nothing to gain from the Song.⁶² This illustrates that Koryŏ also prioritized the policy of maintaining security through a peaceful relationship with the Khitan, and thus shows that the reality of the relationship between the Song and Koryŏ was that they put their own security before anything else.

The polity that had a substantial influence on the Koryŏ-Khitan relations, even more than the Song, was the Jurchen. In the reigns of Great Kings Sŏngjong and Hyŏnjong of Koryŏ, the Khitan expressed its concern over Koryǒ’s relations with not only the Song but the Jurchen. This was because the relationship with the Jurchen directly affected the Khitan. According to the Song text Sanchao beimeng huibian 三朝北盟會編 (Compilation of Documents on the Treaties with the North During Three Reigns), “The Jurchen are people of the old state of Sushenguo 肅愼國 (kr. Sukshin’guk).… In the third year of the Dazhongxiangfu 大中祥符 era (era name of the Song Emperor Zhenzong), the Khitan passed through the [Jurchen] land during its expedition against Koryŏ, and the Jurchen joined forces with Koryǒ to thwart the Khitan’s attack. The Jurchen army numbered merely ten thousand, but their bows and arrows were exquisite and strong, and their aim was excellent. When the fort burned down to ashes, they poured water on it and froze it into ice, and the ice fort stood so strong that [the Khitan soldiers] could not scale it. The Khitan suffered a major defeat, lost their men, and retreated.”^63, This record detailed that Koryŏ and the Jurchen formed a united front against the Khitan in 1010, the first year in the reign of Great King Hyŏnjong of Koryŏ, and showed that the Jurchen had an effect on the Koryŏ-Khitan relations. Song shi 宋史 [History of the Song Dynasty] also records, “[The Khitan] led a large army to invade [Koryŏ] in the third year of the Dazhongxiangfu era, Sun 詢 (meaning Great King Hyŏnjong of Koryŏ) devised a curious plan with the Jurchen and attacked the Khitan army, killing them all.”⁶⁴ These accounts suggest that in war against the Khitan in 1010, Koryŏ found its relations with the Jurchen more helpful in reality than its relations with the Song.

The fact that the Khitan was concerned about the Koryŏ-Jurchen alliance is evidenced by a record of Xiao Hajianu’s statement to Xingzong Khan in 1035 about how the Khitan was unable to properly subdue Parhae, the Jurchen, and Koryŏ even though the three have been forming various strategic alliances among themselves,⁶⁵ and another record in which the Khitan asked about Koryŏ’s relationship with the Jurchen during Koryŏ Minister Yu Ch’am’s visit to the Khitan as an envoy. Moreover, the inscription on “Yelü Renxian muzhiming” 耶 律仁先墓誌銘 (Epitaph for Yelü Renxian), dated 1072 (8th year in the Xianyong 咸雍 era of the reign of Daozong Khan of the Khitan) also illustrates the Khitan’s concern of the movement for alliance between Koryŏ and the Jurchen.

This record illustrates the situation in which five states, including Koryŏ and the Jurchen, formed an alliance to invade the Khitan. While the lack of historical sources makes it difficult to know whether there was actually a joint movement of the five states, it is clear that the Khitan had concerns about an alliance with Koryŏ and the Jurchen from Xiao Hajianu’s statement about Parhae, Koryŏ, and the Jurchen, as such alliances were likely to create serious trouble for the Khitan’s security. It also shows that the Jurchen were one of the most important factors in understanding the Koryŏ-Khitan relations.

The Jurchen became more prominent in the relationship among Koryŏ, the Khitan, and the Song in 1115, after the Jin dynasty was founded. In 1117, upon finding out through the Khitan’s Gao Yaoshi 高藥師 and others that the Jin had occupied the Liaodong region and had been pressuring the Khitan,^67, the Song aimed to join forces with the Jin^68, to attack the Khitan and reclaim the Sixteen Prefectures of Yan and Yun.⁶⁹ However, such situation was not well received by the Khitan or Koryǒ.

During Great King Yejong’s reign, Injong, who was a prince at the time, expressed caution against the Jin while referring to the Khitan as a “brotherly state.” The Song sent the two doctors to Koryŏ around July 1118 (13th year in the reign of Great King Yejong).^71, Given that the Song’s doctors remained in Koryŏ for about two years, Injong seems to have expressed concerns about the Song alliance with the Jurchen between July 1118 and July 1120.⁷²

In 1117 (12th year in the reign of Great King Yejong), prior to the Song doctors’ visit to Koryŏ, the Jin had requested peace with Koryŏ through a letter, in which the Jin’s khan was referred to as an older brother (兄) and the Koryŏ’s king as a younger brother (弟).^73, Koryŏ’s officials adamantly objected to friendship with the Jin. When Kim Puch’ŏl 金富轍 proposed friendship with the Jin, raising concerns about the possibility of armed conflicts, officials of the highest two ranks of the main state organs 宰樞 (kr. chaech’u) snorted and did not care to respond.^74, Presumably the Jin’s attitude would not have been satisfactory at all for Koryŏ, which believed that it was superior to the Jurchen. In a letter to the Jin in August 1119, Koryŏ mentioned that the “Jin originated from Koryŏ,” and the Jin was so offended by the statement that it refused to accept the letter.^75, These events illustrate that the two states were engaged in a tense diplomatic standoff in an effort to gain the upper hand in their relations. Under such circumstances, an alliance between the Song and the Jin was not a welcome one for Koryŏ since it would raise the likelihood of an armed conflict with the Jin, as Kim Puch’ŏl asserted. In 1119, Koryŏ reinforced the fortifications on its border with the Jin, augmenting the fortress walls about one meter higher to defend itself against the Jin.⁷⁶

After an alliance was formed between the Song and the Jin, the Khitan sent Xiao Gongting 蕭公聽 and Yelü Zunqing 耶律遵慶 to Koryŏ in August 1119, and Deputy Commissioner of the Imperial Medical Institute Xiao Zunli 藥院副使 蕭遵禮 in July 1120.^77, Records in the Liao shi state that, in February 1120 (10th year of the Tianqing 天慶 era), the Jin sent an envoy to the Khitan and reproved the Khitan for sending Wulinda Zanmo 烏林答贊謨 to Koryŏ to request military reinforcements.^78, This account confirms that the reason for the Khitan sending envoys to Koryŏ was to request military assistance, and thereby an alliance with Koryŏ. It seems that the Khitan aimed to respond to the Song-Jin alliance by joining forces with Koryŏ. Koryŏ also dispatched Ha Ch’ikbo 河則寶 to the Khitan by boat from Yongju 龍州 in August 1123 (first year in the reign of Great King Injong of Koryŏ), but Ha returned without ever reaching the Khitan.⁷⁹ As the land route had been blocked off by the Jin, it seems that Koryŏ made an attempt to send an envoy by sea route in an effort to thwart the Jin’s threat through an alliance with the Khitan. The four states－Koryŏ, Khitan, Jin, and Song－formed alliances in various combinations at the time, which confirms that national security was a priority over loyalty and great causes among the states in terms of international relations from the 10th to the 12th centuries.

Conclusion

International relations in East Asia from the 10th through the 12th centuries had been understood through a triangular relationship framework with the Khitan and the Song in a bipolar relationship and either Koryŏ or Western Xia as the third state. It is widely acknowledged that this framework has the advantage of simplifying international affairs under restricted conditions, which allows for an easy comprehension of the situation at the time. However, even the Song and the Khitan, which were considered to be major powers at the time, were merely two nations among equals. For example, The relationship between Koryŏ and the Khitan also did not lead to a situation where one country overpowered the other. Of course, there is a lot of room to believe that the Khitan has an overall advantage. However, as can be seen from the fact that the Khitans requested reinforcements from the Song to attack Koryŏ, the Khitans were also not confident that they were overpowering Koryŏ. This shows that the 10th to 12th centuries were a time when one country did not dominate the other. Consequently, the countries in East Asia during that time had to seek allies and strive for survival in response to the shifting international landscape. There are difficulties in understanding the international order of that era based solely on triangular relationships. Therefore, rather than rigidly adhering to the notion of triangular relationships, it would be more reasonable to explore the shifts and changes in the balance of power among East Asian states to understand international affairs of the time.

The Khitan was interested in Koryŏ’s relations with the Jurchen and particularly the Song as both the Jurchen and the Song played pivotal roles in the dynamics between Koryŏ and the Khitan. An alliance between Koryŏ and the Song posed a potential threat to Khitan security. The potential of a threat posed by the Koryŏ-Song alliance prompted the Khitan to deploy substantial military forces and engage in wars with Koryŏ to avert a possible crisis. Following these wars, the Khitan ceased large-scale armed conflicts but remained wary of the Koryŏ-Song alliance. Both Koryŏ and the Song, in turn, relied on each other to maintain a balance of power against the relatively dominant Khitan. The Song valued Koryŏ as a force that countered Khitan power, while Koryŏ saw the Song as a potential ally against the Khitan threats. However, due to geographical barriers, being separated by a sea, and divergent stances at different times, actual military cooperation between the two nations never materialized. As a result, the necessity for mutual support dwindled at times, leading to sporadic displays of hostility. There were clear and inherent limitations hindering the realization of Koryŏ-Song alliance.

In the dynamics between Koryŏ and the Khitan, the Jurchen, a tribe of people forming political entity predating modern nation-states, played a more pivotal role than the Song, which did not share territorial proximity with either Koryŏ or the Khitan. The Jurchen provided military cooperation for Koryŏ during the Khitan invasion of Koryŏ in 1010. Following the rapid ascendancy of the Jurchen(Jin dynasty) in 1115, the Jin’s role became increasingly crucial in relations involving Koryŏ, the Khitan, and the Song. Apart from the Jurchen, the nomadic polity of Zubu, which also did not share territorial or diplomatic ties with Koryŏ, contributed to delaying conflicts between Koryŏ and the Khitan from the Khitan’s rear. These states sought alliances based on their responses to changes in the international sphere, prioritizing self-preservation over mere inter-state alliances or legitimacy. Therefore, rather than confining the relationships among East Asian nations at the time within a rigid triangular framework, understanding the constantly shifting international situations at the time and the fact that all states prioritized their own security would bring us closer to the historical truth.

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