Author of this work considers the Bohai person Gao Mouhan, who was military and political leader in Bohai state, Koryo kingdom and Khitan Empire. He made a big contribution for development of the Liao Empire and destruction of Chinese states. In spite of Gao Mouhan had a big influence for many events in the East Asia, his military and political activities are little-known. Therefore author analyses his activity not only in Liao Empire, but in Koryo too. Gao Mouhan moved between Koryo, areas of former Bohai kingdom and Khitan state. Author considered and analyzed reasons of his immigration, role of Gao Mouhan in events, specifics of development of these countries at that period. The goal of this work are analysis of person and activity by Gao Mohan, study his role for events in East Asian history and consideration materials about this leader. Author uses materials not only in European (Russian, German and English), but in Asian languages (Korean and Chinese) too.