Excerpts from Books and Wikipedia
"Under the benign rule of the Song dynasty (960-1279), China became the world's most prosperous and technologically advanced country. . . . In 1114 the Song Emperor Huizong thought he saw an opportunity to cut the Khitan down to size by supporting a rebellion by their tributaries, the Jurchen people of Manchuria. . . . This soon became a greater threat to the Song empire than the Khitan had ever been. . . . Gaozong, a younger son of Huizong, managed to escape the mass capture of the royal family and declared himself emperor on June 10, 1127. Though unable to reconquer the north, Gaozong established a new capital in southern China at Hangzhou, beginning the Southern song period (960-1126 is known as the Northern Song period), which was ended by the Mongol conquest in 1279." [1001 Days]