The Xiongnu, contemporaries of Rome and Egypt, built their nomadic empire on the Mongolian steppe 2,000 years ago, emerging as Imperial China’s greatest rival and even inspiring the construction of China’s Great Wall. In a new study researchers find that the Xiongnu were a multiethnic empire, with high genetic diversity found across the empire and even within individual extended elite families. At the fringes of the empire, women held the highest positions of power, and the highest genetic diversity was found among low-status male servants, giving clues to the process of empire building that gave rise to Asia’s first nomadic imperial power.