In 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.