Noin-Ula burial site
Many immigrants lived in the Xiongnu pasturelands, but at first they did not mix with the Xiongnu. To be a Xiongnu, one had to be a member of a clan, born of Xiongnu parents. The newcomers were well off, but were outsiders, and could marry only among themselves, not the Xiongnu. Only later did they intermix, increase in numbers, even created a state that existed from 318 to 350 AD.
Proto-Mongols
The Donghu (or Tung Hu, the Eastern Hu), a proto-Mongol and/or Tunguz group mentioned in Chinese histories as existing as early as the 4th century BC. The language of the Donghu, unlike that of the Xiongnu, is believed by modern scholars to be proto-Mongolic. The Donghu were among the first peoples conquered by the Xiongnu. By the 1st century AD, the Donghu had split, along geographical lines in two: the proto-Mongolic Xianbei (Wade–Giles "Hsien-pei") in the north and the Wuhuan in the south. After the Xiongnu were driven back into their homeland by the Chinese (48 AD), the Xianbei (in particular) began moving (from apparently the north or northwest) into the region vacated by the Xiongnu.