Yelü Bei
In 926, the Khitan-led Liao dynasty conquered Balhae and established the autonomous kingdom of Dongdan ruled by the Liao crown prince Yelü Bei, which was soon absorbed into the Liao. Meanwhile, a series of nobilities and elites led by key figures such as crown prince Dae Gwang-hyeon, were absorbed into Goryeo. The Khitan conquest of Balhae was one of the factors behind Goryeo's prolonged hostility against Khitan Liao dynasty. At its start, the kingdom had around 100,000 households and a population of about 500,000. Archaeological evidence suggests that the Balhae culture was an amalgamation of High Tang Chinese, Korean, and Tungusic cultures.