Dai Commandery was first established around 300 during China's Warring States Period by the state of Zhao's King Yong, posthumously known as the Wuling King. The commandery seat—then known as Dai—was southwest of present-day Yuzhou in Hebei. It was the former capital of the independent state of Dai, which had been conquered by King Yong's ancestors around 476. He created Dai Commandery along with its companion commanderies of Yanmen and Yunzhong to consolidate his conquests from invasions of the Loufan and "forest nomads" in 306 and 304. Following the Qin conquest of Zhao, Zhao Jiaattempted to regroup at Dai, declaring himself its king. This Kingdom of Dai was ended by Qin in 222, just prior to the declaration of the Qin Empire two years later.
Qin Empire
Dai Commandery was one of the divisions of the Qin Empire. Its seat—then known as Daixian—continued to be near present-day Yuzhou.
Under the Han, Dai Prefecture formed part of the province of Bingzhou and oversaw 18 counties, both within and beyond the Great Wall. Along with Yunzhong and Yanmen, it also formed part of the Principality of Dai, used as an imperial appanage. The Book of Han records Dai Commandery having 278,754 people living in 56,771 households. The Han administration kept the seat at Daixian near present-day Yuzhou and continued the Qin-era counties, with the addition of:
Xin Empire
Under the short-lived Xin dynasty established by Wang Mang, several of the Han counties were renamed.
Under the Eastern Han, Dai Commandery formed part of the province of Youzhou. Its seat—then known as Gaoliu—was southwest of present-day Yanggao in northeastern Shanxi.
During China's Sixteen Kingdoms Period, both Later Yan and the Northern Wei had commanderies named Dai. Northern Wei's lay to the west, with its seat at Pingcheng. Separate from these, Tuoba Yilu was declared "Duke of Dai" by the Jin in 310 and "King of Dai" by the same court in 315. This XianbeiKingdom of Dai lasted until 376, and its dynasts were responsible for the later state of Northern Wei. It held some lands in northern Shanxi and Hebei but was mostly to their north in what is now Inner Mongolia, with their capital at Shengle.
Dai Commandery continued until its abolishment under the Wen Emperor of Sui, who replaced it in 585 with Dai Prefecture, whose seat was at Guangwu or Yanmen.
