Xiongnu
In the 1920s, Pyotr Kozlov's excavations of the royal tombs at the Noin-Ula burial site in northern Mongolia that date to around the first century CE provided a glimpse into the lost world of the Xiongnu. Other archaeological sites have been unearthed in Inner Mongolia and elsewhere; they represent the Neolithic and historical periods of the Xiongnu's history. Those included the Ordos culture, many of them had been identified as the Xiongnu cultures. The region was occupied predominantly by peoples showing Mongoloid features, known from their skeletal remains and artifacts. Portraits found in the Noin-Ula excavations demonstrate other cultural evidences and influences, showing that Chinese and Xiongnu art have influenced each other mutually. Some of these embroidered portraits in the Noin-Ula kurgans also depict the Xiongnu with long braided hair with wide ribbons, which is seen to be identical with the Ashina clan hair-style. Well-preserved bodies in Xiongnu and pre-Xiongnu tombs in the Mongolian Republic and southern Siberia show both Mongoloid and Caucasian features. Analysis of skeletal remains from sites attributed to the Xiongnu provides an identification of dolichocephalic Mongoloid, ethnically distinct from neighboring populations in present-day Mongolia. Russian and Chinese anthropological and craniofacial studies show that the Xiongnu were physically very heterogenous, with six different population clusters showing different degrees of Mongoloid and Caucasoid physical traits. These clusters point to significant cross-regional migrations (both east to west and west to east) that likely started in the Neolithic period and continued to the medieval Mongolian period.
History of the eastern steppe
In 221 BC China was unified by the Qin dynasty and after a brief civil war, more permanently by the Han dynasty (206 BC – 220 AD). About 209 BC the steppe tribes were united by the Xiongnu. The two unifications were connected in that the nomads had to unite to protect themselves from the now-powerful Chinese and the Xiongnu ruler could strengthen himself with Chinese tribute. In the east, the Xiongnu conquered the Xianbei in Manchuria and in the west they drove the Wusun and Yuezhi westward. The Wusun soon disappeared, but the Yuezhi later had a great career as the Kushans of Afghanistan. In China, after about 75 years of internal consolidation and external tribute, Emperor Wu of Han adopted a forward policy. Zhang Qian went west (138-125 BC) and returned with the first good reports of the Western Regions. During the Han-Xiongnu Wars the southern Xiongnu in Inner Mongolia were subjugated and the northern Xiongnu were driven to northern Mongolia where they were broken up around 89 AD. The Han gained control of the Gansu Corridor and the Tarim Basin with some influence westward. This opened the Silk Road and led to the appearance of Chinese silk in the Roman Empire. As the Han declined the Tarim Basin experienced complex shifts of power between the Chinese, Xiongnu remnants and local rulers.
In the 19th century Western imperialism and industrialism began to impact eastern Asia. Steppe nomadism and many traditional Chinese institutions gradually became obsolete, both economically and militarily. In 1860 Russia annexed north and east Manchuria which soon acquired a Russian population. There was a massive migration of Han Chinese into Manchuria and Inner Mongolia which socially removed these areas from the steppe and attached them to China. When the Manchu dynasty fell in 1912 the Mongols claimed that they had been subject to the Manchus rather than China and were therefore now independent. This Russian-backed independence may have prevented Chinese immigration into the area. In recent decades there has been a significant Han migration into Xinjiang.