South Xiongnu is a Xiongnu that migrated southward and actively sinicized after the split of Xiongnu. In the middle and late Western Han Dynasty, under the constant attack of the Han army, the Huns gradually lost their dominant position in Sino-Hungarian relations and lost a large territory near the Han Dynasty border. The Huns who occupied the land became the servants of the Han army, and the military defeat aggravated the development of internal contradictions. Moderates in the Huns began to seek to give up hostility, learn from and approach the Han nationality, and the war faction gradually lost its dominant position in the Huns. In this situation, the Han Dynasty launched a series of signs of softening in time. So a large number of Huns moved south, came to the sphere of influence of the Han army, accepted the rule of the Han Dynasty, and became Han Chinese. These Huns who actively seek cooperation and integration with the Han nationality are called South Huns.

From the concept of a country, South Xiongnu is a vassal state of Han Dynasty, and it is no longer a vassal state of Xiongnu.

From the national point of view, the southern Xiongnu is still Xiongnu, a Hun with the qualification of "citizen" in the Han Dynasty, and a minority in the Han Dynasty.