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.
Origin of the Huns
There are, however, potential problems with equating the names "Xiōngnú" and "Hun". Maenchen-Helfen notes that the Chinese transcription is only an approximation of their actual name. As proof of its imprecision, he notes that Emperor Wang Mang actually renamed the Xiongnu as the Hsiang-nu, with the first element meaning "to submit", while on bad terms with the group. Later, when on good terms, he renamed them Kung-nu, with the first element meaning "respectful". Christopher Beckwith, moreover, notes that the pronunciation of Xiongnu in Old Chinese is uncertain. While it was likely pronounced "*χoŋnʊ" or "*χʲoŋnʊ" in Middle Chinese, it is possible it was taken into Old Chinese before the change of initial "s" to "χ", meaning it could correspond to an Iranian name like Saka or "skuδa" (Scythian). E.G. Pulleyblank suggested an Old Chinese pronunciation similar to "*flông-nah" and connected this name to a nomadic people attested in Greek as the Phrounoi ("Φροῦνοι").