An Examination of the Koryŏ-Khitan Relations from the 10th to 12th Century through the Balance of Power System

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. The period spanning the 10th to 12th centuries was not characterized by any single nation overpowering others. 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. 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. 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.