
Oghuz Turks began migrating into the area now called Turkey (derived from the Medieval Latin Turchia, i.e. "Land of the Turks") in the 11th century. The process was greatly accelerated by the Seljuk victory over the Byzantines at the Battle of Manzikert. Several small beyliks and the Seljuk Sultanate of Rûm ruled Anatolia until the Mongol 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 and his colleagues, 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 Turkic Council, Joint Administration of Turkic Arts and Culture, Organisation of Islamic Cooperation and the Economic Cooperation OrganizationTurkey's location at the crossroads of Europe and Asia makes it a country of significant geostrategic importance. Given its strategic location, large economy and military strength, Turkey is a major regional power

The victory of the Seljuks gave rise to the Anatolian Seljuk Sultanate; which developed as a separate branch of the larger Seljuk Empire that covered parts of Central Asia, Iran, Anatolia and Southwest Asia. [page needed]
In 1243, the Seljuk armies were defeated by the Mongols, causing the Seljuk empire's power to slowly disintegrate.

During nearly two centuries of decline, the Ottoman Empire gradually shrank in size, military power, and wealth. It entered World War I on the side of the Central Powers and was ultimately defeated. During the war, an estimated 1.5 million Armenians were deported and exterminated in the Armenian Genocide. The Turkish government denies that there was an Armenian genocide and claims that Armenians were only relocated from the eastern war zone. Large scale massacres were also committed against the empire's other minority groups such as the Greeks and Assyrians. Following the Armistice of Mudros on October 30, 1918, the victorious Allied Powers sought to partition the Ottoman state through the 1920 Treaty of Sèvres.
Turkey is a transcontinental[84] Eurasian country. Asian Turkey (made up largely of Anatolia), which includes 97% of the country, is separated from European Turkey by the Bosphorus, the Sea of Marmara, and the Dardanelles (which together form a water link between the Black Sea and the Mediterranean). European Turkey (eastern Thrace or Rumelia in the Balkan peninsula) comprises 3% of the country.[85]
The territory of Turkey is more than 1,600 kilometres (1,000 mi) long and 800 km (500 mi) wide, with a roughly rectangular shape. It lies between latitudes 35° and 43° N, and longitudes 25° and 45° E. Turkey's area, including lakes, occupies 783,562 square kilometres (300,948 sq mi), of which 755,688 square kilometres (291,773 sq mi) are in Southwest Asia and 23,764 square kilometres (9,174 sq mi) in Europe. Turkey is the world's 37th-largest country in terms of area. The country is encircled by seas on three sides: the Aegean Sea to the west, the Black Sea to the north and the Mediterranean to the south. Turkey also contains the Sea of Marmara in the northwest.
The European section of Turkey, East Thrace, forms the borders of Turkey with Greece and Bulgaria. The Asian part of the country, Anatolia, consists of a high central plateau with narrow coastal plains, between the Köroğlu and Pontic mountain ranges to the north and the Taurus Mountains to the south. Eastern Turkey has a more mountainous landscape and is home to the sources of rivers such as the Euphrates, Tigris and Aras, and contains Lake Van and Mount Ararat, Turkey's highest point at 5,165 metres (16,946 ft). Lake Tuz, Turkey's third-largest lake, is a macroscopically visible feature in the middle of the country.
Turkey is divided into seven census regions: Marmara, Aegean, Black Sea, Central Anatolia, Eastern Anatolia, Southeastern Anatolia and the Mediterranean. The uneven north Anatolian terrain running along the Black Sea resembles a long, narrow belt. This region comprises approximately one-sixth of Turkey's total land area. As a general trend, the inland Anatolian plateau becomes increasingly rugged as it progresses eastward.