Chizhishizhuhou Chanyu
The southern Xiongnu were a branch of the eastern Xiongnu that followed the rebellious pretender Huhanye and in 51-53 BC moved en masse within the Han borders under protection of Chinese. Since the times of Huhanye, the status of the southern Xiongnu was loyal allies of the Han Dynasty. The southern Xiongnu enjoyed material support of the old "heqin" treaty, and in return guarded the Chinese northern borders and participated in the Chinese external and internecine conflicts as long as the Chinese court respected their independence. However, when the Han imperial court attempted to appoint an ineligible for the crown Western Jükü-Prince Yufuluo from ineligible Right Wing as a Chanyu, instead of respecting the traditional election, the southern Xiongnu dissented and elected a lawful alternate Hyuibu Gudu-heu. Later they expelled Yufuluo, who had to seek safety in exile at the Han imperial court.
Xiongnu
Barfield attempted to interpret Xiongnu history as well as narrate it. He made the following points: The Xiongnu confederation was unusually long-lived for a steppe empire. The purpose of raiding China was not simply for goods, but to force the Chinese to pay regular tribute. The power of the Xiongnu ruler was based on his control of Chinese tribute which he used to reward his supporters. The Han and Xiongnu empires rose at the same time because the Xiongnu state depended on Chinese tribute. A major Xiongnu weakness was the custom of lateral succession. If a dead ruler's son was not old enough to take command, power passed to the late ruler's brother. This worked in the first generation but could lead to civil war in the second generation. The first time this happened, in 60 BC, the weaker party adopted what Barfield calls the 'inner frontier strategy.' They moved south and submitted to China and then used Chinese resources to defeat the Northern Xiongnu and re-establish the empire. The second time this happened, about 47 AD, the strategy failed. The southern ruler was unable to defeat the northern ruler and the Xiongnu remained divided.