The Xiongnu Empire was a confederacy of nomadic peoples which dominated the north of China from the third century B.C. until the first century B.C. Imagine Genghis Khan’s Mongol army, but a millennium earlier . . . and with chariots. A number of theories exist to explain the Xiongnu’s origins, and at one time some scholars argued that the Xiongnu may have been the ancestors of the Huns. Unfortunately, the Xiongnu left few records of their own behind.What we do know is that Xiongnu raids on China were so devastating that the Qin emperor ordered the earliest construction work on the Great Wall. Nearly half a century later, the Xiongnu’s persistent raiding and demands for tribute forced the Chinese, this time under the Han dynasty, to refortify and expand the Great Wall even further. In 166 B.C., over 100,000 Xiongnu horsemen made it to within 160 kilometers (100 mi) of the Chinese capital before finally being repulsed. It took a combination of internal discord, succession disputes, and conflict with other nomadic groups to weaken the Xiongnu enough for the Chinese to finally assert some semblance of control over their northern neighbors. Still, the Xiongnu were the first, and the longest lasting, of the nomadic Asian steppe empires.