Iran

Iran, also known as Persia and officially as the Islamic Republic of Iran, is a country located in West Asia. It is bordered by Iraq and Turkey to the west, by Azerbaijan and Armenia to the northwest, by the Caspian Sea and Turkmenistan to the north, by Afghanistan and Pakistan to the east, and by the Gulf of Oman and the Persian Gulf to the south. It covers an area of , making it the 17th-largest country. With an estimated population of 86.8 million, Iran is the 17th-most populous country, and the second largest in the Middle East. Its largest city is the capital Tehran, followed by Mashhad, Isfahan, Karaj, Shiraz, and Tabriz. Iran is home to one of the world's oldest civilizations, beginning with the formation of the Elamite kingdoms in the fourth millennium BC. It was first unified by the Medes in the seventh century BC and reached its territorial height in the sixth century BC, when Cyrus the Great founded the Achaemenid Empire, one of the largest empires in history. Alexander the Great conquered the realm in the fourth century BC and it was subsequently divided into several Hellenistic states. An Iranian rebellion established the Parthian Empire in the third century BC, which was succeeded in the third century AD by the Sassanid Empire, a major world power for the next four centuries. Arab Muslims conquered the empire in the seventh century AD, leading to its Islamization; Iran thereafter became a major center of Islamic culture and learning, with its art, literature, philosophy, and architecture spreading across the Muslim world and beyond during the Islamic Golden Age. Over the next two centuries, a series of native Iranian Muslim dynasties emerged before the Seljuk Turks and the Mongols conquered the region. In the 16th century, the native Safavids re-established a unified Iranian state and national identity, and converted the country to Shia Islam. Under the reign of Nader Shah in the 18th century, Iran presided over the most powerful military in the world, though by the 19th century, a series of conflicts with the Russian Empire led to significant territorial losses.