Following the reign of King Seon ( 830 ) , there is no surviving written records of Balhae . Some scholars believe that the 946 eruption of Paektu Mountain may have caused a national level catastrophe leading to its final fall to the Khitan Liao Dynasty , based on records of massive population displacement of Balhae people to the Liaodong peninsula of the Khitan empire and the Korean peninsula of Goryeo . A significant territory of what was used to be Balhae was mostly depopulated , especially around the Paektu volcano , which was at the heart of Balhae territory . Other historians believe that ethnic conflicts between the ruling Goguryeos and underclass Mohe weakened the state . The Khitans were centered in Liaoning and Inner Mongolia , which overlaps Balhae 's purported territories in the west . A Khitan invasion took the capital of Balhae after a 25-day siege in 926 . After defeating Balhae , the Khitans established a puppet state founded by its new Khitan rulers , the Dongdan Kingdom , which was annexed by Liao in 936 . Some Balhae aristocrats were forced to move to Liaoyang , but Balhae 's eastern territory remained politically independent
946 eruption of Paektu Mountain
946 eruption of Paektu Mountain
Balhae