During the wars between the Song dynasty and Jurchen-led Jin dynasty (1115–1234), the Song capital, Kaifeng, was conquered by Jin forces in 1127. Remnants of the Song dynasty retreated south and established the Southern Song dynasty, with Emperor Gaozong (r. 1127–1162) as their ruler. Kong Duanyou (), who then held the Duke Yansheng title, also moved to the south and settled in Quzhou, Zhejiang, where the southern branch of Confucius's descendants was created. Kong Duancao (), Kong Duanyou's brother, remained in Qufu, Shandong, where he called himself the "acting Duke Yansheng". Later on, the Jin dynasty recognised Kong Duancao's legitimacy. This resulted in a north–south split among the descendants of Confucius. Historians regarded the southern branch as the "di" (legitimate) successor to Confucius's line, while the northern branch is seen as a "shu" (offshoot) branch.