Rezā Shāh
In 1925, Reza Khan, a former Brigadier-General of the Persian Cossack Brigade, deposed the Qajar dynasty and declared himself king (shah), adopting the dynastic name of "Pahlavi", which recalls the Middle Persian language of the Sasanian Empire. (He had chosen the last name Pahlavi for himself in November 1919.) By the mid-1930s, Reza Shah's strong secular rule caused dissatisfaction among some groups, particularly the clergy, who opposed his reforms, but the middle and upper-middle class of Iran liked what Rezā Shāh did. In 1935, Rezā Shāh issued a decree asking foreign delegates to use the term Iran in formal correspondence, in accordance with the fact that "Persia" was a term used by Western peoples for the country called "Iran" in Persian. His successor, Mohammad Reza Pahlavi, announced in 1959 that both Persia and Iran were acceptable and could be used interchangeably.