The 20th century began with Iran (then known as Persia) under the weak Qajar dynasty, with significant British and Russian influence.

In the 1920s, an army officer named Reza Khan seized power and established a new dynasty, crowning himself Reza Shah Pahlavi.

Reza Shah pursued a program of modernization, centralization, and secularization, similar to Atatürk's in Turkey.

During World War II, he was forced to abdicate by the Allies, and his son, Mohammad Reza Pahlavi, became the new Shah.

In 1953, a coup d'état backed by the U.S. and UK overthrew the democratically elected Prime Minister, Mohammad Mosaddegh, and restored the Shah's absolute power.

The Shah's rule was characterized by pro-Western policies, oil wealth, and political repression by his secret police, the SAVAK.

Growing opposition to his rule, led by the exiled cleric Ayatollah Khomeini, culminated in the Islamic Revolution of 1979.

The revolution overthrew the Shah and established the Islamic Republic of Iran, a theocracy.

This was followed by the Iran hostage crisis and the long, brutal Iran-Iraq War.

The 1979 revolution fundamentally transformed Iran's society and its relationship with the rest of the world.