Iran is a country in Western Asia. It is bordered to the northwest by Armenia and Azerbaijan; with Kazakhstan and Russia across the Caspian Sea; to the northeast by Turkmenistan; to the east by Afghanistan and Pakistan; to the south by the Persian Gulf and the Gulf of Oman; and to the west by Turkey and Iraq. Comprising a land area of 1,648,195 km2 (636,372 sq mi), it is the 18th-largest in the world. With 78.5 million inhabitants, Iran is the world's 17th most populous nation and the second-largest nation in the Middle East after Egypt. Iran is the only country that has both the Caspian Sea and Indian Ocean coastline. It has long been of geostrategic importance because of its central location in Eurasia and Western Asia, and its proximity to the Strait of Hormuz.
Iran is home to one of the world's oldest civilizations, beginning in 3200–2800 BC. Iran reached the pinnacle of its power in 550 BC, which at its greatest extent comprised major portions of the ancient world, making it the largest empire the world had yet seen.
Iran is a major regional and middle power, exerting considerable influence in international energy security and the world economy through its large reserves of fossil fuels, which include the largest natural gas supply in the world and the fourth-largest proven oil reserves. It hosts Asia's 4th-largest number of UNESCO World Heritage Sites.