History of Mongolia
Although the Xiongnu finally had been split into two parts in AD 48, the Xianbei (or Hsien-pei in Wade–Giles) had moved (apparently from the east) into the region vacated by the Xiongnu. The Xianbei were the northern branch of the Donghu (or Tung Hu, the Eastern Hu), a proto-Mongol group mentioned in Chinese histories as existing as early as the 4th century BC. The language of the Donghu is believed to be proto-Mongolic to modern scholars. The Donghu were among the first peoples conquered by the Xiongnu. Once the Xiongnu state weakened, however, the Donghu rebelled. By the 1st century AD, two major subdivisions of the Donghu had developed: the proto-Mongolic Xianbei in the north and the Wuhuan in the south.
Xiongnu
The ruler of the Xiongnu was called the Chanyu. Under him were the Tuqi Kings. The Tuqi King of the Left was normally the heir presumptive. Next lower in the hierarchy came more officials in pairs of left and right: the "guli", the army commanders, the great governors, the "dunghu" and the "gudu". Beneath them came the commanders of detachments of one thousand, of one hundred, and of ten men. This nation of nomads, a people on the march, was organized like an army.