Goryeo–Khitan War

Goryeo–Khitan relations

Silla declined from the late 9th century and was succeeded by Goryeo after the Later Three Kingdoms period. In 926, the Liao dynasty conquered Balhae, and its last crown prince and survivors fled to Goryeo, uniting the two successor states of Goguryeo.

Taejo of Goryeo accepted the Balhae refugees as kin and pursued northern expansion. In 942, the Khitan sent 50 camels as a gift, but Goryeo refused it, banished the envoy, and starved the camels under a bridge. Hyeonjong later ordered preparations for conflict with Liao.

First Invasion

In 993, the Liao invaded Goryeo's northwestern frontier with a force alleged to be 800,000 strong. After a stalemate, negotiations led to Goryeo ending relations with Song, paying tribute to Liao, and adopting Liao's calendar. Through diplomat Sŏ Hŭi, Goryeo gained land between the Liao border and the Yalu River, then held by Jurchen tribes, citing Goguryeo's past claim. Liao withdrew, but Goryeo continued communicating with Song and built fortresses in the new territory.

Second Invasion

In 1009, General Kang Cho of Goryeo led a coup, killing King Mokjong and establishing military rule. The Liao attacked in 1010 with 400,000 troops, claiming to avenge Mokjong. Kang Cho blocked the first attack but was defeated and executed in the second. King Hyeonjong fled to Naju as the capital was sacked and burned.

Liao withdrew to avoid a counterattack. Goryeo sued for peace, but the Liao emperor demanded Hyeonjong's personal submission and key border areas; the court refused, leading to a decade of hostility. Liao attacked in 1015, 1016, and 1017 with indecisive results.

Aftermath

The following year, Liao assembled another large army for invasion, but neither side could gain a decisive victory. In 1020, King Hyeonjong resumed sending tribute, and in 1022 the Khitans officially recognized his reign. A Khitan envoy invested Hyeonjong as king, and his successor Wang Heum was also invested by the Liao court. Goryeo broke off relations with Song, and Liao ceded territory around the Yalu to Goryeo.

Relations remained peaceful until the end of the Liao dynasty. The 1022 peace treaty required Goryeo to acknowledge vassalage and release detained Liao envoys. After 1022, Goryeo had no diplomatic relations with Song until 1070, except for an isolated embassy in 1030, likely related to a Balhae rebellion in Liao that was quickly suppressed. Goryeo adopted Liao's reign title in the fourth month of 1022, though according to Bielenstein, Goryeo maintained relations with Song, Hyeonjong kept his own reign title, and the two states concluded peace as equals.

Did You Know?

• At the Battle of Gwiju, Kang Kam-ch'an annihilated most of the Liao army, with only a few thousand survivors.