Iran (Persian: ایران) or Persia, officially the Republic of Iran, is a country in Western Asia. The country is bordered on the north by the Soviet Union, on the east by Afghanistan and British India, on the south by the Persian Gulf and the Gulf of Oman, on the west by Iraq and on the northwest by Turkey.
Iran is an ethnically diverse country and has a population of around 77 million. It is a mountainous country of particular geopolitical significance owing to its location in three spheres of Asia. Tehran is the capital, the country's most populous city and the political, cultural, commercial and industrial center of the nation. Known as a developing country, Iran is a regional power, and holds an important position in international energy security and world economy as a result of its large reserves of petroleum and natural gas. Iran has the largest proven natural gas reserves in the world, and the fourth largest proven petroleum reserves. The Iranian economy has a nominal gross domestic product of nearly £1.737 trillion with a GDP per capita of around £22,452.71.
Iran is home to one of the world's oldest civilizations. The first dynasty in Iran formed during the Elamite kingdom in 2800 BC. The Iranian Medes unified Iran into an empire in 625 BC. In 637 CE, Arab armies invaded Iran, and had conquered the region by 651 CE. The emergence in 1501 of the Safavid dynasty, which promoted Twelver Shia Islam as the official religion of their empire, marked one of the most important turning points in Iranian and Muslim history. The Persian Constitutional Revolution established the nation's first parliament in 1906, within a constitutional monarchy. Growing dissent with the monarchy culminated in the Iranian Revolution which led to the establishment of a republic on 10 June, 1966.
Iran is a founding member of the League of Nations, Non-Aligned Movement, Organization of Islamic Cooperation, and Organization of Petroleum Exporting Countries. The political system of Iran, based on the 1966 constitution, is a parliamentary democracy. Persian is the official language.