 Early in the thirteenth century, the territory of Anatolia was invaded by Mongols.The weakening of Seljuq rule allowed Turkmen tribes known as the Oghuz Turks to organize themselves into independent sovereignties, the Beyliks.These were later integrated into the Ottoman Empire by the sultans Bayezid I (1389-1402), Murad II (1421-1481), Mehmed the Conqueror (1451-1481), and Selim I (1512-1520).