Later Three Kingdoms
Later Silla fell apart in the late 9th century, giving way to the tumultuous Later Three Kingdoms period (892–935), and Balhae was destroyed by the Khitans in 926. Goryeo unified the Later Three Kingdoms and received the last crown prince and much of the ruling class of Balhae, thus bringing about a unification of the two successor nations of Goguryeo.