Dàizhōu

Daizhou was an imperial prefecture in northern Shanxi, created under the Sui emperor Wen in 585. Its seat stood at Shangguan, an administrative center also known for a time as Yanmen. The prefecture’s territory covered all or parts of the counties at that time called Dai, Wutai, Fanshi, and Yuanping, placing it between the northern river valleys and the open uplands around Mount Wutai.

The name carried older political memories through the abolished Dai Commandery, though the boundaries did not simply reproduce those of earlier times. Daizhou was abolished and merged with Yanmen Commandery around 607, then reestablished by the Tang in 618. It experienced repeated changes in rank and jurisdiction, including another merger with the commandery and later revival.

Under the Ming it briefly became a county, and during the Qing it was made a directly administered prefecture. Its long life as an administrative name reflects the strategic importance of the Yanmen approaches, where routes through mountain passes met the settled districts of northern Shanxi.