Duan tribe

The Duan was a tribe of Xianbei ethnicity during the era of Sixteen Kingdoms in China. They were a powerful tribe in the Liaoxi region and played a key role during the fall of the Western Jin dynasty. Unlike the Xianbei tribes of the steppe, the Duan were unique in that they were established within the borders of China. They ruled over their dukedom of Liaoxi and later established the Duan Qi state, although neither were considered part of the Sixteen Kingdoms. The tribe was conquered by the Murong-led Former Yan in 338, but remained politically influential as maternal relatives of the Murong.

Background
The founder of the Duan tribe was Rilujuan (or Jiulujuan), a Xianbei who was sold as a slave to a Wuhuan family in Yuyang Commandery known as the Kunuguan (庫辱官). When a famine broke out in Yuyang, the Kunuguan sent him to Liaoxi Commandery to scour for food, but he instead took the opportunity to escape. He gathered a group of exiles and established a base in Lingzhi (令支, in present-day Qian'an, Hebei), a city that had been abandoned during the Han dynasty. Rilujuan was succeeded by his younger brother Qizhen, who was then succeeded by his son, Duan Wuwuchen. By the Western Jin dynasty, the tribe had grown to have 30,000 families and around 45,000 cavalry soldiers under their wing.

Liaoxi dukedom (303–338)
During the War of the Eight Princes, the Jin Inspector of You province, Wang Jun sought to secure his position by allying with the surrounding Xianbei and Wuhuan people. He entered a marriage alliance with Duan Wuwuchen, offering him a fiefdom as the "Duke of Liaoxi" in return for his tribe's military service. Wang Jun's barbarian auxiliaries were a deciding factor in the civil wars, with the Duan playing a role in his victory against the Prince of Chengdu, Sima Ying in 304. The Duan continued to support Wang Jun in his war against the Xiongnu state of Han-Zhao, battling the Jie warlord, Shi Le with much success. Wuwuchen died in around 310, succeeded by his son, Duan Jilujuan.

In 313, after some negotiations, Jilujuan agreed with Shi Le to break off relations with Wang Jun and withdraw from the conflict. Wang Jun was defeated by Shi Le in 314, but soon after, Jilujuan's brother, Duan Pidi, led a branch of the Duan loyal to Jin and seized control of Wang Jun's old capital in Jicheng. The Duan was effectively split into two, but civil war only broke out following the death of Jilujuan in 318. That year, Jilujuan's cousin, Duan Mopei, seized power from his uncle, Duan Shefuchen, and fought with Pidi over full control of the tribe.

In 321, Pidi was captured and later killed by Shi Le's state of Later Zhao, making Mopei the sole leader of the Duan. At this point, the Duan's state of Liaoxi stretched from Yuyang Commandery to the Liao River. After Mopei died in 325, his brother and successor, Duan Ya was quickly overthrown by his cousin, Duan Liao after he attempted to move the capital. Throughout his reign, Duan Liao fought with the rival Murong-Xianbei tribe in Liaodong, but suffered repeated losses. In 338, the Murong, who by now had established the Former Yan, allied with the Later Zhao to destroy the Duan. Duan Liao was defeated and surrendered to Former Yan, thus ending the Duan's independent state.

Later history
While Duan Liao was killed for rebelling in 339, the Duan remained a prominent family within the Former Yan and their successors states of Later Yan, Western Yan and Southern Yan as maternal relatives due to a number of their women such as Duan Yuanfei and Duan Jifei marrying into the Murong family. Other Duan members fled to Later Zhao where they became generals, most notably Duan Lan and Duan Qin. During the collapse of the Later Zhao, Duan Lan's son, Duan Kan, founded the short-lived Duan Qi state in Shandong in 350, while Duan Qin declared himself the Emperor of Zhao in 352. However, both were eventually captured and executed by the Former Yan.

Language
Shimunek classifies Duan as a "Serbi" (i.e., para-Mongolic) language. Shimunek's "Serbi" linguistic branch also includes Taghbach, Tuyuhun, and Khitan.