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.
Han dynasty
The Eastern Han (), also known as the Later Han (), formally began on 5 August 25, when Liu Xiu became Emperor Guangwu of Han. During the widespread rebellion against Wang Mang, the state of Goguryeo was free to raid Han's Korean commanderies; Han did not reaffirm its control over the region until AD 30. The Trưng Sisters of Vietnam rebelled against Han in AD 40. Their rebellion was crushed by Han general Ma Yuan (d. AD 49) in a campaign from AD 42–43. Wang Mang renewed hostilities against the Xiongnu, who were estranged from Han until their leader Bi (比), a rival claimant to the throne against his cousin Punu (蒲奴), submitted to Han as a tributary vassal in AD 50. This created two rival Xiongnu states: the Southern Xiongnu led by Bi, an ally of Han, and the Northern Xiongnu led by Punu, an enemy of Han.