 The Six Prefectures also revolted against Tang, until Tang army dispersed them in 722.Between 155 and 166, the Xianbei (*"Särpi") (Ch.鮮卑, Wade–Giles Hsien-pi, Hsien-pei), a former vassal tribe of the Xiongnu, united under Tanshihuai conducted a series of campaigns against Northern Xiongnu, eventually defeating them and forcing them to flee west, which started a series of Xiongnu migrations (93 CE - circa 380 CE) westward to southern Siberia and Central Asia.