The Jurchens in the Yalu River region were tributaries of Goryeo since the reign of Wang Geon, who called upon them during the wars of the Later Three Kingdoms period, but the Jurchens switched allegiance between Liao and Goryeo multiple times, taking advantage of the tension between the two nations. As the balance of power on the Liao-Goryeo border shifted, the Jurchens, who lived around the border between the two states, began to expand their power. Finally, in 1115, the Jurchen chieftain Wányán Āgǔdǎ founded the Jin dynasty in Manchuria, and began to attack the Liao dynasty. In 1125, Jin troops captured the Emperor Tianzuo of Liao with help from the Song dynasty, who encouraged the Jin dynasty in the hope of gaining territories they lost to the Liao before. Remnants of the Liao imperial clan fled to Central Asia, where they established the Western Liao dynasty. Many of them were forced to surrender to the Jin dynasty.