Dai County, also known by its Chinese name Daixian, is a county in Xinzhou, Shanxi Province, China. Its county seat at Shangguan is also known as Daixian. The county has an area of 1,729 km2 (668 sq mi) and had a population of 178,870 at the time of the 2020 census. The county is the home of the AAAAA-rated Yanmen Pass Scenic Area along the Great Wall, as well as the Bianjing Drum Tower, the Ayuwang Pagoda, and the Zhao Gao Forest Park.

Xinzhou, ancient name Xiurong (秀荣), is a prefecture-level city occupying the north-central section of Shanxi Province in the People's Republic of China, bordering Hebei to the east, Shaanxi to the west, and Inner Mongolia to the northwest.