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.
Tarim Basin
Around 200 BCE, the Yuezhi were overrun by the Xiongnu. The Xiongnu tried to invade the western region of China, but ultimately failed and lost control of the region to the Chinese. The Han Chinese wrested control of the Tarim Basin from the Xiongnu at the end of the 1st century under the leadership of General Ban Chao (32–102 CE), during the Han-Xiongnu War. The Chinese administered the Tarim Basin as the Protectorate of the Western Regions. The Tarim Basin was later under many foreign rulers, but ruled primary by Turkic, Han, Tibetan, and Mongolic peoples.