One of the world's earliest permanently settled regions, present-day Turkey was home to important Neolithic sites like Göbekli Tepe, and was inhabited by ancient civilisations such as the Hattians, other Anatolian peoples and Mycenaean Greeks. Following the conquests of Alexander the Great which started the Hellenistic period, most of the ancient regions in modern Turkey were culturally Hellenised, which continued during the Byzantine era. The Seljuk Turks began migrating in the 11th century, and the Sultanate of Rum ruled Anatolia until the Mongol invasion in 1243, when it disintegrated into small Turkish principalities. Beginning in the late 13th century, the Ottomans united the principalities and conquered the Balkans, and the Turkification of Anatolia increased during the Ottoman period. After Mehmed II conquered Constantinople (Istanbul) in 1453, Ottoman expansion continued under Selim I. During the reign of Suleiman the Magnificent, the Ottoman Empire became a global power. From the late 18th century onwards, the empire's power declined with a gradual loss of territories. Mahmud II started a period of modernisation in the early 19th century. The Young Turk Revolution of 1908 restricted the authority of the Sultan and restored the Ottoman Parliament after a 30-year suspension, ushering the empire into a multi-party period. The 1913 coup d'état put the country under the control of the Three Pashas, who facilitated the Empire's entry into World War I as part of the Central Powers in 1914. During the war, the Ottoman government committed genocides against its Armenian, Assyrian and Pontic Greek subjects. After its defeat in the war, the Ottoman Empire was partitioned.