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What Type of Relationship Did the Early Goryeo Dynasty have with the Khitans?

The Khitans emerged as a new powerhouse in Northeast Asia during the chaotic, final period of the Tang Dynasty. Yelu Abaoji founded Khitan in 916, calling himself the emperor, and in 926 he overthrew Balhae. His immediate successor, Taizong Yelu Deguang, brought the later Tang Dynasty to the ground in 928, allowing Governor Shi Jingtang to establish the Later Jin. Khitan occupied the 16 states, thus allowing them to emerge as a powerful authority in the northern region.

The relationship between Goryeo and Khitan dates back to the year 922 (the 5th year of Taejo). Goryeo had been hostile towards Khitan because Balhae, its brother country, was overthrown by the Khitan. Thus, in the year 942 (the 25th year of Taejo), when the Khitan envoys visited Goryeo with 50 camels, King Taejo exiled the 30 envoys and starved the camels to death under the Manbu Bridge. The Khitans had sent camels as a gift to promote goodwill and friendship between themselves and Goryeo. The gift had really been sent with the intention to remove the threat that Goryeo posed, as a war between the Khitans and the Later Jin was on the horizon. Eventually, the Later Jin was brought down by Khitan in the year 946. King Taejo had intended to recapture Goguryeo’s older land after unifying the Later Three Kingdoms, however his dream was shattered because the Khitans had invaded Balhae first. Thus, King Taejo's target for attack shifted from Balhae to Khitan. King Taejo tried to take Balhae by forming a connection with Goguryeo. However, the Khitans took no retaliatory measures against King Taejo’s anti-Khitan actions because of its looming battle against the Later Jin.

Since its foundation, Goryeo continued its northward policy, reaching the Yalu River basin in the period of King Seongjeong. At the time, the Khitans built castles in Wigu, Jinhwa and Naewon (presumed to be Geumdongdo near Yalu River) along the Yalu River to ward off Goryeo’s further advances. As Goryeo and Khitan met head-on in the Yalu River basin, war clouds began to gather.

Goryeo-Khitan Wars and the Battle of Gwiju

The First War

As the Khitans invaded in October 993 (12th year of Seongjong), King Seongjong let Park Yang-yu, Seo Hui and Choi Ryang form army units and deploy them in key areas in the northwest region. King Seongjong had advanced to Anbukbu but retreated after hearing that the Khitan’s General Xiao Sunning had captured Goryeo’s leading general, Yun Seo-an, in Bongsangun, just 10 kilometers southeast of Gwiju. After occupying Bongsangun, General Xiao demanded that Goryeo surrender.

General Xiao claimed that the Khitans came to defeat Goryeo as Goryeo intruded into Khitan’s territory, although his country had already taken and inherited Goguryeo’s land. This was seen as an attempt to crush Goryeo’s determination to advance to the north. He then claimed that 800,000 Khitan's troops had invaded Goryeo. General Xiao's intimidation tactics worked on the Goryeo officials, as some advocated to seek for peace by surrendering the land north of Seogyeong to the Khitans.

Seo Hui reacted strongly to this proposition, insisting that Goryeo make a decision after meeting with the Khitans to figure out their intentions. Nevertheless, King Seongjong accepted the proposition for peace and ordered for the military provisions that were being stored in Seogyeong to be distributed to the residents. However, the remaining provisions were dumped into the Taedong River to prevent enemy troops from accessing and eating the food. Because of these actions, some officials and citizens began to question the king's competence. In response to these accusations, Seo Hui suggested that the king come up with proactive countermeasures.

In fact, drawing a peace treaty with Khitan went against King Taejo's dying wishes. Thus, Seo Hui suggested looking for a diplomatic compromise first, even if it meant ceding its land, noting that Goryeo would face an even graver crisis if they ended the war in a peace treaty.

Meanwhile, while waiting for an answer from Goryeo, Khitan's army invaded Anyungjin, south of the Cheongcheon River, but suffered a defeat. Even General Xiao Sunning could not be sure of their own victory in this war against Goryeo. The general was worried that if his army advanced deeply into Goryeo's territory, they would be blocked with no way out since Goryeo was blocking the Yalu River basin. He was also concerned about being able to supply food for the hundreds of thousands of Khitan troops. Additionally, General Xiao was concerned that because a considerable number of the Khitan soldiers were from Balhae or were Jurchen people, many of them might surrender to Goryeo if the war was showing to be disadvantageous to Khitan's side. All of these circumstances led to Goryeo and Khitans seek for peace.

When Seo Hui arrived at the peace summit, General Xiao accused Goryeo of intruding into Goguryeo's territory and communicating with the Song Dynasty, even though Goryeo had inherited Silla. Seo Hui countered this claim by alleging that Goryeo was the country that had inherited Goguryeo and that Goryeo was unable to make exchanges with the Khitan because of the Jurchen people living near the Yalu River.

As negotiations proceeded smoothly, Goryeo accepted the conditions that the dynasty would now have a peaceful relationship with Khitan while cutting its ties with the Song Dynasty. In return, Goryeo would drive out the Jurchen people and secure the areas near the Yalu River. In comparison, Khitan gave up its key positions, which led to the public belief that Goryeo scored a one-sided diplomatic victory. However, it is unlikely that Khitan - who was known to have had its own national administration plan and foreign policy just 60 years after its foundation - believed they had made a mistake because of the Seo Hui's scheme. If the Khitans made concessions, they would have thought that their decision was advantageous to them at the time.

The Khitans aimed to prevent Goryeo’s advances further northward by establishing its boundaries with Goryeo. Additionally, by cutting off Goryeo’s relationship with Song, Khitan was able to prepare for its invasion of Song. Furthermore, with Goryeo suppressing the Jurchen people, Khitan would have fewer boarder threats. Thus, the Khitans are presently known to have attained their goals of boundary formation and diplomatic relations establishment.

War with the Khitan durings the Period of King Hyeonjong and the Battle of Gwiju

In February 1009, Goryeo notified the Khitan of King Mokjong’s death and King Hyeonjong’s subsequent ascent to the throne. In April of the same year, Goryeo dispatched an envoy to celebrate the birthday of the Khitan’s king and in order to emphasize that its relationship with the Khitan still remained valid. In return, however, the Khitan's King Shengzong led 400,000 troops directly to Goryeo, under the pretext of emphasizing their vigorous vigilance over the Goryeo Kingdom (as Gang Jo’s coup dethroned King Mokjong and enthroned Hyeonjong). The actual reason for the invasion was triggered by the concern that Goryeo might ally with Song to attack the Khitan from both sides.

In October 1010, Goryeo appointed Gang Jo as commander and Lee Hyeon-woon and Jang Yeon-woo as deputy commanders. These new commanders were to lead 300,000 troops deployed to Tongju (Seoncheon, North Pyeongan Province) in order to prepare for the Khitans’ invasion. King Shengzong of Khitan attacked Heunghwajin, but was blocked by commander Yang Gyu, and thus deterred to the south. As Gang Jo was defeated and captured at the Tongju Castle, the Khitans rallied to capture Gaegyeong. At this time, King Hyeonjong escaped to Naju through Samrye, Gongju and eventually proposed peace on the condition that he could attend the Khitan's royal court. King Shengzong killed Gang Jo and captured Gaegyeong but because of the strong resistance of the Goryeo army, he failed to conquer Heunghwajin, Guju and Seogyong. King Shengzong, realizing his escape route might be cut off, hurriedly retreated after confirming his aforementioned conditions of a ceasefire and King Hyeonjong’s attendance at the Khitan's royal court.

After the retreat of the Khitans, Goryeo dispatched an envoy in April of 1011 (the 2nd year of Hyeonjong) to express appreciation for the Khitans’ withdrawal and made other efforts to maintain peace by sending envoys again in October and November. However, despite the persistent demands from the Khitans for King Hyeonjong’s presence at the Khitan’s royal court, Goryeo was reluctant to cooperate. Goryeo responded finally in June of 1012, explaining that their king was ill and could not go visit the Khitan’s royal court at the time. Irked by this response, King Shengzong killed Ha Gong-jin, a hostage, and threatened to reclaim six counties in Gangdong.

It is said that the reason for the Khitans' continuous invasions due to two reasons: the fact that Goryeo violated their promise and their king never showed up at the Khitan's royal court, and the fact that they had to return to Goryeo the six counties in Gangdong. However, the fact that Khitan's international standing had changed since the "Jeonyeon Peace Treaty" also played a major role in Khitan's decision to attack. Khitan and Song had been called equal states both ruled by emperors. However, the Khitans had implicit superiority over Song, and they wanted complete submission, as opposed to perfunctory submission from Goryeo.

Since then, the Khitans continued to invade Goryeo and eventually occupied Boju. Occupying Boju enabled the Khitans to secure a bridgehead near the Yalu river which, in turn, helped them attack Goryeo. This led Goryeo to rebel and resume correspondence with Song; in 1017 Goryeo began using Song's era name. Goryeo's friendly relationship with Song prompted the Khitans' massive invasion.

In October of 1018 (the 9th year of Hyeonjong), Khitan appointed Xiao Baiya to lead 100,000 troops in an invasion on Goryeo. Goryeo thus named Gang Gam-chan as commander and Gang Min-cheom as deputy commander who together led 208,000 troops to Yeongju. Given the size of the mobilized army, one could guess Goryeo's determination. When the Khitan invaded with 100,000 forces, Goryeo then defended with 200,000 soldiers.

In December 1018, Goryeo hid 12,000 calvary in the mountains of Heonghwaijin where they blocked a stream by stitching cowhide together with large ropes. When the Khitan forces started crossing the stream, the Goryeo army destroyed the dam and sent the Khitan forces into disarray. Xiao then led his troops straight to Gaegyeong where they were defeated by the Goryeo army led by Gang and other generals. The Khitans suffered a string of defeats near Gaegyeong and faced counterattacks from Goryeo, even in their retreat back home. In February of the following year at the Battle of Gwiju, the Khitans suffered a particularly devastating defeat. Dead bodies littered the field, prisoners were taken alive, and innumerable horses, camels, armor and weapons were left behind; only a few thousand survived.

Countered by Goryeo's forces' sound defense, the Khitans retreated, and the two countries concluded the war with a peace treaty. Aware that Goryeo would not be brought to submission by force, Khitan did not mention the six counties in Gangdong in the treaty. And Goryeo, exhausted by the drawn-out wars, accepted the pact while also accepting the Khitans' occupation of Boju.

The military bases that the Khitan had obtained through the three invasions of Goryeo were in Naewon and Boju (also called Poju). Since this was the location of the bridgehead that the Khitan had secured within Goryeo's territory, Goryeo repeatedly demanded its return even after the peace treaty had been signed, but to no avail. In fact, a key factor that played into Goryeo’s decision to build the Cheollijangseong in the period of King Deokjong was to defend against the threat that was posed by the Khitans stationed in Naewon and Boju.

War with the Khitan in the Period of King Hyeonjong and the Battle of Gwiju

East Asia during the Goryeo Dynasty was characterized as being a pluralistic age in which a few countries with similar power levels coexisted, rather than being an era in which one superpower wielded its vast influence to coerce neighboring countries to pay taxes. The diplomatic relationship between Goryeo and Khitan can be roughly divided into three periods. The period during which there was no exchange between the two countries lasted from 942 (the 25th year of Taejo) until 993 (the 12th year of Seongjong); the period of war between the two countries began in 993 and ended in 1019 (the 10th year of Hyeonjong); the period of peace was from 1020 (the 11th year of Hyeonjong) to 1125 (the 3rd year of Injong).

The relationship between Goryeo and Khitan began in the period of Taejo. Taejo made it clear that he had no intention of communicating with them by starving the camels that the Khitan had sent to death and sending the envoys into exile only because the Khitan had destroyed Balhae. From then on, their relationship remained hostile.

The Khitans began to invade Goryeo in 993 and the two countries were in a state of war for about 30 years until the peace treaty of 1020 (11th year of Hyeonjong). During this period of war, the Khitans were mainly assailants, however Goryeo was never on the defense unilaterally. During the first war, the Khitans realized that Goryeo would not submit easily and eventually settled for peace after some compromising. The Khitans established a friendly relationship with Goryeo in exchange for forcing Goryeo to cut ties with Song. They also accepted the Goryeo's possession of the six counties in Gangdong.

Khitan, who had defeated Song and signed the "Jeonyeon Peace Treaty," invaded Goryeo again to verify its status as a tributary to the Khitans. At this time, Khitan retreated after Hyeonjong promised to appear at the Khitan's royal court. As mentioned before, the Goryeo did not keep its promise which resulted in the Khitan's occupation of Boju and their demand of the return of the six states in Gangdong. Angered by this, the Goryeo resumed relations with Song, and Khitan allowed Xiao Biaya to invade Goryeo. However, the Khitans were defeated at the fortress of Gwiju which concluded in a peace treaty.

As a result of the three-year war, the Khitans were able to secure the Yalu River basin and succeeded in changing the direction of Goryeo's diplomacy from Song to Khitan. Although Goryeo was paying taxes to Khitan, the wars were never unilaterally in favor of the Khitans. Rather, the Khitans suffered a devastating defeat in the third war and Goryeo's international standing rose with its victory. This bode well for Goryeo, as the Jurchen people in the northeast region volunteered to pay taxes to Goryeo after the war against the Khitans ended.

After being at war with the Khitans, Goryeo acknowledged that the central forces of East Asia had shifted towards Khitan and maintained the diplomatic course of coexisting with them. At that time, however, East Asia was not in a unified hierarchical relationship under one force, but in the state of relatively equal coexistence among Goryeo, Khitan, Song, Xi Xia, etc. It is judged that this coexistence stemmed from Goryeo's victory against the Khitans.