History of Mongolia
Although the Xiongnu finally had been split into two parts in AD 48, the Xianbei (or Hsien-pei in Wade–Giles) had moved (apparently from the east) into the region vacated by the Xiongnu. The Xianbei were the northern branch of the Donghu (or Tung Hu, the Eastern Hu), a proto-Mongol group mentioned in Chinese histories as existing as early as the 4th century BC. The language of the Donghu is believed to be proto-Mongolic to modern scholars. The Donghu were among the first peoples conquered by the Xiongnu. Once the Xiongnu state weakened, however, the Donghu rebelled. By the 1st century AD, two major subdivisions of the Donghu had developed: the proto-Mongolic Xianbei in the north and the Wuhuan in the south.
Yueban
Between 155 and 166, the Xianbei or Syanbi (Ch. , Wade–Giles Hsien-pi, Hsien-pei), a former vassal tribe of the Xiongnu, united under Tian-Shih-huai 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. (The Xiongnu have often been linked to the Huns that later invaded Europe from the Eurasian steppe, although the link has never been conclusively established. Likewise the Yueban of late antiquity have sometimes been known as the "Central Asian Huns".)