In 993, Khitans under General Xiao Sunning invaded Korea, but retreated after truce negotiations with minister Seo Hui of Goryeo, establishing friendly relations between the two nations. In 1004, Khitans invaded China. Chinese forces were terribly defeated, and the Chinese were forced to pay tribute to the Liao emperor. However, beginning in the summer of 1018, the Khitans constructed a bridge across the Yalu River.