When "Persia" became "Iran" 21 March 1935In the Western world, Persia (or one of its cognates) was historically the common name for Iran. In 1935, Reza Shah asked foreign delegates to use the term Iran, the historical name of the country, used by its native people, in formal correspondence. Since then, in the Western World, the use of the word "Iran" has become more common. This also changed the usage of the terms for Iranian nationality, and the common adjective for citizens of Iran changed from Persian to Iranian. In 1959, the government of Shah Mohammad Reza Pahlavi, Reza Shah Pahlavi's son, announced that both "Persia" and "Iran" could officially be used interchangeably
On the 25th December [1934] the Persian Ministry for Foreign Affairs addressed a circular memorandum to the Foreign Diplomatic Missions in Tehran requesting that the terms "Iran" and "Iranian" might be used in official correspondence and conversation as from the 21st March next instead, of the words "Persia" and "Persian" hitherto in current use. His Majesty's Minister in Tehran has been instructed to accede to this request.
The decree of Reza Shah Pahlavi affecting nomenclature duly took effect on 21 March 1935.Modern reconstruction of the ancient world map of Eratosthenes from c. 200 BC, using the names Ariana and Persis
