Iran is one of the oldest nations in the world, with a history dating back tens of thousands of years. The country's first great city, Susa, was built on the central plateau around 3200 B.C.
In 559 B.C., the Persian Empire arose in southwestern Iran and conquered the Mesopotamians and Egyptians. The empire eventually extended from the Mediterranean Sea to what is now Pakistan, but it was conquered by the Greeks in 330 B.C.
Around 260 B.C., nomads called Parni ousted the Greeks and ruled for some 500 years. The Sassanids came into power in A.D. 224, and in A.D. 642, Persia became part of the Islamic Empire. In 1501, the kings, or shahs, of the Safavid Empire began their reign.
In the late 18th century, foreign powers, including Russia and Britain, took control of parts of Persia. In 1921, a Persian army officer named Reza Khan took control and sought to end outside influence. In 1935, he renamed the country Iran. His son, Mohammad Reza Pahlavi, became shah in 1941.
In 1979, the Iranian government was changed to an Islamic Republic by Islamic Revolution.