Border issue in the fight of three states for hegemony on the Korean peninsula in the 4th-5th centuries a. d

Prior to 4 th-5 th centuries, major military conflicts did not arise between the three Korean states. The majority of the border clashes in 1 st-3 rd centuries were sporadic and partook of the one state’s raid on the territory of another. The boundaries of Silla as the weakest of the Three Kingdoms, was the most frequently attacked by its nearest neighbors. Poor military organization had led to the fact that Kings of Silla repeatedly appealed the Japanese for help to repel attacks of Koguryo. The 4 th century saw the situation on the Korean peninsula change dramatically. The complete formation of Three Korean states expanded their territory at the expense of weaker neighbors and led to the emergence of the border issue between Koguryo, Baekche and Silla, claiming the right to leadership on the Korean peninsula. In this situation, the relationship between the Three Kingdoms could not be resolved by peaceful means. Every new neighboring areas are the result of expanding the boundaries of the state and were seen as potential targets for future gains. That desire for the acquisition of new land and the tax-paying population served as motivation for the most frequent wars among the three Korean states, which led to the rapid change of the boundaries of the Korean Peninsula. The most active struggle of Koguryo, Baekche and Silla states was conducted for the land in the basin of the Han River that was a buffer zone between the areas controlled by the Three countries. The expansion of the Koguryo to the south and Baekche to the north of the Korean peninsula led to regular boundary conflicts in the district. Han was a buffer zone between the areas controlled by the two countries. As a result, having pushed the border south of Baekche, Koguryeo took possession of the Hangan river basin, at the same time turning Ye tribal lands on the east coast of the Korean peninsula in their possession as well. In addition, Baekche lost the diplomatic war for external allies. It allowed Koguryo to use its military might to seize land Paekche. In the beginning of the 5th century, when Baekche was forced to cede some of their territories of Koguryo, the conclusion of the military-political alliances came to play an important role in solving the border issue on the Korean Peninsula. Since then, the main purpose of the ambassadors sent from one of three Korean states to another Korean state or China, was to find an ally in the fight against a third country or undermine the already existing union.