With the triump of Malazgirt battle in 1071, the Anatolian Seljuks ruled the region from the beginning of dense Turkish migration to Anatolia until the Mongol invasion in 1243. After the Mongol invasion much small Turkish chiefdom emerged.From the late 13th century onwards, the Ottomans became the most important force in Eurasia and Africa, establishing a great empire over Anatolia, Southeast Europe, West Asia and North Africa. The Empire reached its peak during the 15th and 17th centuries, especially during the reign of Suleiman I. After the 1683 II. Vienna siege and the Battle of the Holy Alliance of 1699, the Turks started to withdraw from the European lands. The Ottoman Empire experienced a long period of decline. In the wake of World War I, the Ottoman Empire fell victim to the war with the Allied Power and was occupied by Entente powers. With the victory of the War of Independence against the occupying forces, the Republic of Turkey was established by Mustafa Kemal Ataturk in 1923.The Republic of Turkey borders with Bulgaria in the northwest, with Greece in the west, Georgia to the northeast, Armenia, Iran and Azerbaijan in the east, Iraq and Syria in the southeast. Turkey is surrounded by the Mediterranean Sea, the Aegean Sea in the west and the Black Sea in the north. The Sea of Marmara seperates Asia from Europe. Turkey has geostrategic power due to its geographical location between Europe, the Middle East and Asia.Turkey, hosting a variety of cultures in the territory, is a democratic, secular, unitary, constitutional Republic. The official language of the country is Turkish and 99 percent of the population is Muslim. Being a member of the Council of Europe, NATO, OECD, OSCE and the G-20 group, Turkey is integrated into the Western world. Turkey became a member of the European Economic Community in 1963. It joined the EU Customs Union in 1995 and began negotiating for full membership with the European Union in 2005. Turkey also is part of organizations such as the Turkish Council, the International Organization of the Turkish Culture, the Organization of the Islamic Cooperation and the Economic Cooperation. Today, Turkey owing to its fast growing economy and diplomatic initiatives are accepted as a regional power.