Turks began migrating into the area now called Turkey ("land of the Turks") in the 11th century. The process was greatly accelerated by the Seljuk victory over the Byzantine Empire at the The Battle of Manzikert, or Malazgirt. Several small beyliks and the Seljuk Sultanate of Rûm ruled Anatolia until the Mongol Empire's invasion. Starting from the 13th century, the Ottoman beylik united Anatolia and created an empire encompassing much of Southeastern Europe, Western Asia and North Africa. After the Ottoman Empire collapsed following its defeat in World War I, parts of it were occupied by the victorious Allies. A cadre of young military officers, led by Mustafa Kemal Atatürk, organized a successful resistance to the Allies; in 1923, they would establish the modern Republic of Turkey with Atatürk as its first president.
Turkey is a democratic, secular, unitary, constitutional republic, with an ancient cultural heritage. Turkey has become increasingly integrated with the West through membership in organizations such as the Council of Europe, NATO, OECD, OSCE and the G-20 major economies. Turkey began full membership negotiations with the European Union in 2005, having been an associate member of the European Economic Community since 1963 and having reached a customs union agreement in 1995. Turkey has also fostered close cultural, political, economic and industrial relations with the Middle East, the Turkic states of Central Asia and the African countries through membership in organizations such as the Organisation of the Islamic Conference and the Economic Cooperation Organization. Given its strategic location, large as well as powerful economy and army, Turkey is classified as a major regional power.