Al-Mas'udi composed his Kitab al-Tanbih wal-ishraf in the years 955 and 956, finishing it not long before his death. Based in part on earlier historical-geographical works, it offers a description of astronomical and meteorological phenomena, the divisions of the earth, the seas, ancient nations, universal chronology, and then the history of Islam until the caliphate of al-Muti' (r. 946-74).