The Iranian Revolution or the Islamic Revolution was a series of events that culminated in the overthrow of the Pahlavi dynasty in 1979. The revolution led to the replacement of the Imperial State of Iran by the Islamic Republic of Iran, as the monarchical government of Shah Mohammad Reza Pahlavi was superseded by Ruhollah Khomeini, an Islamist cleric who had headed one of the rebel factions. The ousting of Mohammad Reza Pahlavi, the last Shah of Iran, formally marked the end of Iran's historical monarchy.
In 1953, the CIA- and MI6-backed 1953 Iranian coup d'état overthrew Iran’s democratically elected Prime Minister, Mohammad Mossadegh, who had nationalized the Anglo-Persian Oil Company. The coup reinstated Mohammad Reza Pahlavi as an absolute monarch and significantly increased United States influence over Iran.