Yanmen Commandery was an administrative subdivision (jùn) of the state of Zhao established c. 300 BC and of northern imperial Chinese dynasties until AD 758. It occupied lands in what is now Shanxi and Inner Mongolia. Its first seat was at Shanwu (near present-day Youyu, Shanxi); its later seats moved southeast to the more defensible sites at Yinguan (within present-day Shuozhou, Shanxi) and Guangwu (near present-day Daixian, Shanxi).