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.
Huns
Recent scholarship, particularly by Hyun Jin Kim and Etienne de la Vaissière, has revived the hypothesis that the Huns and the Xiongnu are one and the same. De la Vaissière argues that ancient Chinese and Indian sources used "Xiongnu" and "Hun" to translate each other, and that the various "Iranian Huns" were similarly identified with the Xiongnu. Kim believes that the term Hun was "not primarily an ethnic group, but a political category" and argues for a fundamental political and cultural continuity between the Xiongnu and the European Huns, as well as between the Xiongnu and the "Iranian Huns".