considered the Donghu to be the Hu proper, yet elsewhere he considered Xiongnu to be also Hu. Ancient China often came in contact with the Xianyun and the Xirong nomadic peoples. In later Chinese historiography, some groups of these peoples were believed to be the possible progenitors of the Xiongnu people. These nomadic people often had repeated military confrontations with the Shang and especially the Zhou, who often conquered and enslaved the nomads in an expansion drift. During the Warring States period, the armies from the Qin, Zhao and Yan states were encroaching and conquering various nomadic territories that were inhabited by the Xiongnu and other Hu peoples. The Zhao–Xiongnu War is a notable example of these campaigns. Pulleyblank argued that the Xiongnu were part of a Xirong group called Yiqu, who had lived in Shaanbei and had been influenced by China for centuries, before they were driven out by the Qin dynasty. Qin's campaign against the Xiongnu expanded Qin's territory at the expense of the Xiongnu. After the unification of Qin dynasty, Xiongnu was a threat to the northern board of Qin. They were likely to attack the Qin dynasty when they suffered natural disasters. State formation The first known Xiongnu leader was Touman, who reigned between 220-209 BC. In 215 BC, Chinese Emperor Qin Shi Huang sent General Meng Tian on a military campaign against the Xiongnu. Meng Tian defeated the Xiongnu and expelled them from the Ordos loop, forcing Touman and the Xiongnu to flee north into the Mongolian Plateau. In 210 BC, Meng Tian died, and in 209 BC, Touman's son Modu became the Xiongnu Chanyu. In order to protect the Xiongnu from the threat of the Qin dynasty, Modu Chanyu united the Xiongnu into a powerful confederation. This transformed the Xiongnu into a more formidable polity, able to form larger armies and exercise improved strategic coordination. Two years later, in 207 BC, the Qin dynasty fell, and after a period of internal conflict, it was replaced by the Western Han dynasty in 202 BC. This period of Chinese instability was a time of prosperity for the Xiongnu, who adopted many Han agriculture techniques such as slaves for heavy labor and lived in Han-style homes. After forging internal unity, Modu Chanyu expanded the Xiongnu empire in all directions. To the north he conquered a number of nomadic peoples, including the Dingling of southern Siberia. He crushed