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.
History of the Han dynasty
The Eastern-Han court colonized and periodically reasserted the Chinese military presence in the Western Regions only as a means to combat the Northern Xiongnu. Han forces were expelled from the Western Regions first by the Xiongnu between 77–90 CE and then by the Qiang between 107–122 CE. In both of these periods, the financial burdens of reestablishing and expanding western colonies, as well as the liability of sending financial aid requested by Tarim-Basin tributary states, were viewed by the court as reasons to forestall the reopening of foreign relations in the region.