|Commanders and leaders|
Gang Jo †
Yang Gyu †
|2nd invasion:Approximately 300,000;
3rd invasion: Approximately 208,000
|1st invasion: Approximately 60,000;
2nd invasion: Approximately 400,000;
3rd invasion: Approximately 100,000
During the Three Kingdoms of Korea period, Goguryeo occupied the northern Korean Peninsula and parts of Manchuria and inner Mongolia. With Goguryeo's fall in 668, Silla unified the Three Kingdoms, while northern parts of Goguryeo territory were briefly occupied by Silla's ally Tang Dynasty China. A former Goguryeo general revived Goguryeo's Manchurian territory as the new kingdom of Balhae.
Right after the fall of Goguryeo, Turkic peoples (called Göktürks) were divided and eventually driven out from most of Central Asia by the Tang Dynasty. Another Turkic tribe, the Uyghurs, replaced the Göktürks but their control was not very strong.
As Balhae, the Uyghur and the Tang Dynasty weakened, the Khitan people, a nomadic confederation located in Manchuria and eastern Mongolia, grew stronger and began to expand their territory. Following Tang's fall in 907, China experienced a long period of civil war.
In 911, threatened by Khitan expansion, Balhae sought assistance from the declining Silla of the Korean Peninsula. Records stated that Balhae also requested help from Silla's successor dynasty Goryeo during the Later Three Kingdoms.
In 922, the Khitan leader Yelü Abaoji sent horses and camels to Goryeo as gifts of friendship. However, when Balhae fell to the Khitan a few years later, King Taejo embraced refugees from Balhae and pursued a policy of northern expansion (possibly enabled by the absence of a fellow Korean kingdom in what was once Goguryeo territory). In 942, the Khitan sent another 50 camels to Goryeo, but this time Taejo refused the gift, exiled the envoy to an island, and had the camels starved to death.
Succeeding Goryeo rulers continued the anti-Khitan policy. Jeongjong raised an army of 300,000 to defend against the Khitan. Gwangjong built fortresses along the northwest, and aggressively developed the military fortifications of present-day Pyongan and Hamgyong provinces.
In 962, Gwangjong of Goryeo allied with Song Dynasty in central China and pursued a northern expansion policy. Additionally, some Balhae refugees had formed a small state called Jeong-an Kingdom in mid-Yalu River region and allied with Song and Goryeo against the Khitan.
The Khitan eventually regained internal stability under the strong leadership of Emperor Shengzong, who sought to counter regional isolation. After conquering Jeongan-guk in 986 and attacking Jurchen tribes in lower Yalu in 991, the Khitans initiated attacks against Goryeo.
In 993, the Khitan invaded Goryeo's northwest border with 800,000 troops. They forced Goryeo to end its tributary relations with the Song dynasty, to become a Liao tributary state and to adopt Liao's calendar. With Goryeo's agreement of these requirements, the Khitan withdrew. Liao gave Goryeo permission to incorporate the land between the border of Liao and that of Goryeo, which was occupied by Jurchen tribes that were troublesome to Liao, up to the Yalu River. In spite of the settlement, Goryeo continued to communicate with Song, having strengthened its defenses by building fortresses in the newly gained northern territories.
In 1010, the Khitan attacked Goryeo again during an internal Goryeo power struggle. King Hyeonjong was forced to flee the capital, which was occupied and burnt. The Khitan forces withdrew after Goryeo admitted the Khitan's suzerainty over it.
When Goryeo continued to refuse to submit or return the northern territories, the Khitan attacked once more. Goryeo generals, including Gang Gam-chan, were able to inflict heavy losses on the Khitan army in the Battle of Kwiju in 1018. In the next year, however, the Liao assembled another large army. Understanding the difficulty of achieving a decisive victory, the two nations signed a peace treaty in 1022.
- Twitchett & Tietze 1994, p.101: "Third invasion, 1018-19".
- Nahm 1988, p. 89.
- Twitchett & Tietze 1994, p.111.
- Twitchett & Tietze 1994, p. 103.
- Ebrey & Walthall 2014, , p. 171, at Google Books: Liao forces invaded Goryeo territory in 993. Instead of pushing for total victory, the Khitans negotiated a peace that forced Goryeo to adopt the Liao calendar and end tributary relations with Song (a violation of King Taejo’s testamentary injunction never to make peace with the Khitan)."
- Hyun 2013, p. 106: "the Khitan army attacked Goryeo, who was forced to accept the status of a Liao tributary in 994."
- Yun 1998, pp.63-65.
- Hatada, Smith Jr & Hazard 1969, p. 52: "In the thirteenth year of the reign of King Sŏngjong (994), Koryŏ submitted to the Khitan and adopted their calender".
- Simons 1995, p. 95: "In 994, during the reign of King Songjong, Koryo was forced to acknowledged the dominance of Khitan".
- Twitchett & Tietze 1994, p.103: "The Korean king was invested with his title by the Liao emperor."
- Yun 1998, p.64: "By the end of the negotiation, Sô Hûi had ... ostensibly for the purpose of securing safe diplomatic passage, obtained an explicit Khitan consent to incorporate the land between the Ch’ôngch’ôn and Amnok Rivers into Koryô territory."
- Twitchett & Tietze 1994, p.102: "Until the 980s Khitan-Koryǒ relations had been at arm’s length, for the Jurchen tribes and Ting-an had provided a buffer zone between Koryǒ's northern frontier and the Liao border". p.103: "Koryǒ was left free to deal with the Jurchen tribes south of the Yalu Valley".
- Hyun 2013, p.106: "Even though the Goryeo court agreed to set up tribute exchanges with the Liao court, that same year [=994] it also sent an envoy to the Song court to appeal, but in vain, for military assistance against the Khitan."
- Twitchett & Tietze 1994, p.103.
- Ebrey & Walthall 2014, , p. 171, at Google Books: "In 1010, on the pretext that the rightful king had been deposed without the approval of the Liao court, the Khitan emperor personally led an attack that culminated in the burning of the Goryeo capital."
- Simons 1995, p. 95: "a prelude to more invasions during the reign of King Hyonjong (1010-1031) and the occupation of Kaesong, the Koryo capital."
- Hatada, Smith Jr & Hazard 1969, p. 52: "in the reign of King Hyŏnjong (1010-1031) there were numerous Khitan invasions, and even the capital Kaesŏng was occupied."
- Simons 1995, p. 93: "a second Liao incursion resulted in heavy losses, the sacking of Kaesong, and the imposition of Liao suzerainty over the Koryo state."
- Twitchett & Tietze 1994, p.112.
- Ebrey, Patricia Buckley; Walthall, Anne (2014), Pre-Modern East Asia: To 1800: A Cultural, Social, and Political History, Third Edition, Boston, MA: Wadsworth, Cengage Learning, ISBN 978-1-133-60651-2.
- Hatada, Takashi; Smith Jr, Warren W.; Hazard, Benjamin H. (1969), A History of Korea, Santa Barbara, CA: ABC-Clio, ISBN 0-87436-064-1.
- Hyun, Jeongwon (2013), Gift Exchange among States in East Asia during the Eleventh Century (Thesis (Ph.D.)), University of Washington.
- Nahm, Andrew C. (1988), Korea: Tradition & Transformation: A History of the Korean People, Elizabeth, NJ: Hollym, ISBN 0-930878-56-6.
- Simons, Geoff (1995), Korea: The Search for Sovereignty, New York, NY: St. Martin's Press, ISBN 0-312-12531-3.
- Twitchett, Denis; Tietze, Klaus-Peter (1994), "The Liao", in Franke, Herbert; Twitchett, Denis (eds.), The Cambridge History of China, Volume 6, Alien Regime and Border States, 907-1368, Cambridge: Cambridge University Press, pp. 43–153, ISBN 0-521-24331-9.
- Yun, Peter I. (1998), Rethinking the Tribute System: Korean States and northeast Asian Interstate Relations, 600-1600 (Thesis (Ph.D.)), University of California, Los Angeles.