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–Xiongnu War
Due to the many losses inflicted on the Xiongnu, rebellion soon broke out and former enslaved people rose up in arms. Around 80 BC, the Xiongnu attacked the Wusun in a punitive campaign and soon the Wusun monarch requested military support from the Han empire. In 72 BC, the joint forces of the Wusun and Han invaded the territory of the Luli King of the Right. Around 40,000 Xiongnu people and many of their livestock were captured before their city was sacked after the battle. The very next year, various tribes invaded and raided the Xiongnu territory from all fronts; Wusun from the west, Dingling from the north, and Wuhuan from the east. The Han forces had set out in five columns and invaded from the south. According to "Hanshu", this event marks the beginning of Xiongnu decline and the dismantlement of the confederation.