A former country in southwestern Asia, now called Iran. The ancient kingdom of Persia became the domain of the Achaemenid dynasty in the 6th century BC. Under Cyrus the Great, Persia became the center of a powerful empire that included western Asia, Egypt, and parts of eastern Europe; it was eventually overthrown by Alexander the Great in 330 BC. The country was conquered by Muslim Arabs between AD 633 and 651. It was renamed Iran in 1935.