高句麗의 東蒙古経略

The Conquest of East Mongolia by Koguryo

The conquest was realised in 395 by the Great King Gwang-Gae-To himself over Biryo which was the old Pilryo part, one of the ancient Khitan eight parts around the Sira Muren riverside. The conflicts between Jaycan and Koguryo produced in A.D. 479 the division of Didouyu to which the scholars agree nowadays as the area around the Xilingol League, the largest step area in the inner Mongolia. By this division, Koguryo deconstructed the ancient Khitan eight parts, so the diverse groups of Khitan either escaped to North Wi or became dominated by Koguryo. In 581~600 A.D. the rivalities between Koguryo, Turk and Sui over the Khitan groups became deepened in East Mongolia. And the Wuchanzhen warlords, the military group for the Sui and Tang Empire, worried about the Koguryo’s desperate pursuit of the hegemony over Mal´Gal and Khitan. So we can postulate these rivalities as one of the major causes for the war between Koguryo and Sui-Tang.