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.
Hexi Corridor
During the Han–Xiongnu War, Han China expelled the Xiongnu from the Hexi Corridor in 121 BCE and even drove them from Lop Nur when King Hunye surrendered to Huo Qubing in 121 BCE. The Han acquired a territory stretching from the Hexi Corridor to Lop Nur, thus cutting the Xiongnu off from their Qiang allies. Again, Han forces repelled a joint Xiongnu-Qiang invasion of this northwestern territory in 111 BCE. After 111 BCE, new outposts were established, four of them in the Hexi Corridor, namely Jiuquan, Zhangye, Dunhuang, and Guzang (Wuwei).
From roughly 115–60 BCE, Han forces fought the Xiongnu over control of the oasis city-states in the Tarim Basin. Han was eventually victorious and established the Protectorate of the Western Regions in 60 BCE, which dealt with the region's defense and foreign affairs.