Xiongnu
The Xiongnu () were a confederation of nomadic peoples who, according to ancient Chinese sources, inhabited the eastern Asian Steppe from the 3rd century BC to the late 1st century AD. Chinese sources report that Modu Chanyu, the supreme leader after 209 BC, founded the Xiongnu Empire.
History of Mongolia
During the next century, as Chinese strength waned, border warfare between the Chinese and the Xiongnu was almost incessant. Gradually the nomads forced their way back into Gansu and the northern part of what is now China's Xinjiang. In about the middle of the 1st century AD, a revitalized Eastern Han dynasty (AD 25-220) slowly recovered these territories, driving the Xiongnu back into the Altai Mountains and the steppes north of the Gobi. During the late 1st century AD, having reestablished the administrative control over southern China and northern Vietnam that had been lost briefly at beginning of this same century, the Eastern Han made a concerted effort to reassert dominance over Inner Asia.
The concept of Mongolia as an independent power north of China is seen in the letter sent by Emperor Wen of Han to Laoshang Chanyu in 162 BC (recorded in the Hanshu):
The identity of the ethnic core of Xiongnu has been a subject of varied hypotheses and some scholars, including A.Luvsandendev, , Henry Howorth, Rashpuntsag, Alexey Okladnikov, Peter Pallas, Isaak Schmidt, Nikita Bichurin and Byambyn Rinchen, insisted on a Mongolic origin.