Datong is a prefecture-level city in northern Shanxi Province of North China, located a few hundred kilometers west by rail from Beijing with an elevation of 1,040 meters (3,410 ft). It has a population of 3,318,057 at the 2010 census of whom 1,447,150 live in the built up area made of 3 out of 4 urban districts (City, Mining and Nanjiao). Near here was the Beidi kingdom of Tai which was conquered by the Zhou dynasty in 457BC. It bordered on the Hu nomads and traded in horses. Tai was later a commandery or county. The town was founded as Pingcheng in 200 BC during the Han Dynasty, after the Battle of Baideng between the Han and the Xiongnu.