Han dynasty
To the north of China proper, the nomadic Xiongnu chieftain Modu Chanyu (r. 209–174 BC) conquered various tribes inhabiting the eastern portion of the Eurasian Steppe. By the end of his reign, he controlled Manchuria, Mongolia, and the Tarim Basin, subjugating over twenty states east of Samarkand. Emperor Gaozu was troubled about the abundant Han-manufactured iron weapons traded to the Xiongnu along the northern borders, and he established a trade embargo against the group. In retaliation, the Xiongnu invaded what is now Shanxi province, where they defeated the Han forces at Baideng in 200 BC. After negotiations, the "heqin" agreement in 198 BC nominally held the leaders of the Xiongnu and the Han as equal partners in a royal marriage alliance, but the Han were forced to send large amounts of tribute items such as silk clothes, food, and wine to the Xiongnu.
Xiongnu
Yap, apparently describing the early period, places the Chanyu's main camp north of Shanxi with the Tuqi King of the Left holding the area north of Beijing and the Tuqi King of the Right holding the Ordos Loop area as far as Gansu. Grousset, probably describing the situation after the Xiongnu had been driven north, places the Chanyu on the upper Orkhon River near where Genghis Khan would later establish his capital of Karakorum. The Tuqi King of the Left lived in the east, probably on the high Kherlen River. The Tuqi King of the Right lived in the west, perhaps near present-day Uliastai in the Khangai Mountains.