Why was Iran commonly called Persia in the West for centuries?

The name "Persia" originated from Persis—a region in southern Iran known as Pārs or Parsa (modern Fārs)—which served as the homeland for the Achaemenid dynasty.12

When ancient Greeks first encountered the Achaemenids during their period of political expansion, they identified the people and their territory by the name of this southern region. As the Achaemenids and later the Sasanian dynasty—also native to Persis—extended their influence across the Iranian plateau, the name "Persia" was gradually applied by Greeks and other Westerners to the entire country.21

While the local population has traditionally referred to their land as Iran, meaning "Land of the Aryans," the term Persia remained the standard designation in the West for centuries. The two names were often used interchangeably until 1935, when the Iranian government officially requested that the international community use the name Iran.123