History of the Islamic Republic of Iran
The Islamic Republic of Iran is the current Iranian state that has existed since 1979, under the rule of a supreme leader and a Islamic theocracy. One of the most dramatic changes in government in Iran's history was seen with the 1979 Iranian Revolution where Shah Mohammad Reza Pahlavi was overthrown and replaced by Ayatollah Ruhollah Khomeini.
Source: Wikipedia — History of the Islamic Republic of Iran (CC BY-SA 4.0)