Turkey is a Eurasian country that stretches across the Anatolian peninsula in Southwestern Asia and the Balkan region of Southeastern Europe. Turkey borders eight countries: Bulgaria to the northwest; Greece to the west; Georgia to the northeast; Armenia, Iran and the Nakhichevan exclave of Azerbaijan to the east; and Iraq and Syria to the southeast. In addition, it borders the Black Sea to the north; the Aegean Sea and the Sea of Marmara to the west; and the Mediterranean Sea to the south. Turkey is a democratic, secular, constitutional republic whose political system was established in 1923 after the fall of the Ottoman Empire. It is a founding member of the United Nations, the OIC, the OECD and the OSCE, a member state of the NATO since 1952 and the Council of Europe since 1949, and is currently in accession negotiations with the European Union, being an associate member since 1964. Due to its strategic location straddling Europe and Asia, Turkey has been a historical crossroad between eastern and western cultures. The geographic area has been a keystone in the birth and development of many of the world's greatest civilisations.