The prefaces to this work, written by two contemporaries, Wang Shiqi (1551–1618), a military strategist, and Du Chengshi (who gained his jin shi degree in 1601), an official at the Bureau of Justice, indicate that the author was Wu Yunzhong, a late 16th–early 17th century military strategist. Wu’s name, with a brief biography, was mentioned in a local history entitled Caozhou Fu zhi (Gazetteer of Caozhou Prefecture), according to which, after Wu Yunzhong received his jin shi degree in 1598, he became a vice censor in chief and an education intendant. He was sent by imperial order on an inspection tour to two frontier towns, Xuanhua and Datong, where he carried out a thorough investigation of local government and the military, cleaned up corruption, and saved large amounts of money, thereby becoming highly respected. This work, Xuanyun yue fa [bang shi] (Military penal codes in Xuanyun region: Public notices) provides details on military laws and the codes for officers in the areas bordering Mongol lands, and it contains valuable information on the Ming court’s relations with the Mongols and the border regions. It focuses on the period from 1368 to 1600, covering most of the Ming dynasty.