Goryeo's Most Well-known Negotiator and Diplomat, Seo Hui
Seo Hui (942-998) was a civil official of the early period of the Goryeo dynasty (918-1392). He is best known for his excellent skills in diplomacy, having stopped an invasion by the Khitans in 993 via diplomatic negotiations which were successful due to his understanding of Korean history and his keen insight into East Asian international relations at the time.
Seo Hui was born to a powerful regional family, with his father having served in the king’s advisory council. He, too, became a high-ranking official after having successfully passing the state examination (gwageo) in 960, and eventually became the head of the Supreme Council (Taebo naesaryeong).
Seo first demonstrated his skills in diplomacy in 982, when he helped re-establish diplomatic relations between Song China and Goryeo. In 993, the Khitans, led by General Xiao Sunning (K. So Sonyeong), invaded Goryeo on the basis of Goryeo’s northern expansion policy and its friendly diplomatic relations with Song. General Xiao successfully overtook Bongsan County (present-day North Hwanghae province, North Korea) and demanded surrender.
After an attempted peace treaty met with further demands of surrender, King Seongjong (r. 981-997) decided to give the land north of Seogyeong (a secondary capital of Goryeo and present-day Pyeongyang, North Korea) to the Khitans. However, Seo Hui persuaded the king otherwise, speculating that the Khitans' threats were actually because they feared Goryeo, pointing out that though the Khitans had successfully taken over Bongsan, they made no more advancements but merely noisy threats.
Around this time, General Xiao attempted another attack, but was defeated. So, he ordered a meeting with Goryeo officials, and Seo Hui volunteered to be the one to go. After Seo Hui rejected demands that he bow to General Xiao, citing that a vassal is only to bow to “his majesty” the king, the two began talks that went as follow:
"Xiao: Your country arose in Silla territory. Goguryeo territory is in our possession. But you have encroached on it. Your country is connected to us by land, and yet you cross the sea to serve China. Because of this, our great country came to attack you. If you relinquish land to us and establish a tributary relationship, everything will be all right.
Seo: That is not so. Our country is in fact former Goguryeo, and that is why it is named Goryeo and has a capital at Seogyeong. If you want to discuss territorial boundaries, the Eastern Capital of your country is within our borders.... Moreover, the land on both sides of the Amnokgang River is also within our borders, but the Jurchens have now stolen it.... If you tell us to drive out the Jurchens, recover our former territory, construct fortresses, and open the roads, then how could we dare not to have [tributary] relations." 
General Xiao conceded to Seo Hui’s argument and removed the troops. Goryeo agreed to tributary relations with the Khitans. For the next three years, Goryeo removed Jurchen tribes who had encroached the area east of the Amnokgang River, and set up six new fortresses in the region to protect Goryeo territory.
By justifying the policy of northern expansion using the historical fact of Goryeo being the successor of Goguryeo, and also acknowledging and addressing the Khitan’s problems with the Jurchens, Seo Hui was able to improve relations with the Khitans and prevent further military conflict.
- The Revival of Goguryeo - Goryeo
- Seo Hui
- State examination
- Supreme Council(Goryeo)
- Song China
- Xiao Sunning (Khitans)
- Bongsan County
- King Seongjong (Goryeo)
- Seogyeong, i.e. Pyeongyang
- Amnokgang River
- Excerpt, with altered Romanization, from Lee, Peter H; Baker, Donald; Ch'oe, Yongho; Kang, Hugh H W; Kim, Han-Kyo, eds. (1997). "Sŏ Hŭi: Arguments on War [from Koryŏ sa chŏryo 2:49b-52b]". Sourcebook of Korean Civilization. 1. New York: Columbia University Press. pp. 298–301.