Iran is one of the world's oldest civilizations, with settlements dating back to 4000 BCE. The Muslim conquest of Persia from 633–656 was a turning point in Iranian history and led to the Islamization of Iran during the eighth to tenth centuries, which the reader will see remains important to modern culture and politics in Iran.
In the 20th century, the "Pahlavi Era" stretched from 1925 until 1979, the year of the Iranian Revolution. This period began under the rule of Reza Shah, a ruler who valued nationalism and militarism while practicing censorship and propaganda within the country. While he did bring about modernization and reform, this reform has been criticized as too centralized and fast. Problems arose between the government and devout Muslims since some of the consequences of modernization included the free mixing of men and women in society and encouragement of women to unveil themselves. Though Iran remained officially neutral during World War II, it was occupied by the Allied forces; these occupying forces deposed Reza Shah in 1941, replacing him with his son Mohammed Reza Shah. Again, the rule of Mohammed Reza Shah was both a time of modernization and of great oppression. One of Mohammed Reza Shah's biggest critics was the Ayatollah Khomeini, who, even from exile, fomented a revolution that peaked in 1978 and 1979.
The Shah fled Iran on January 16, 1979, and the Ayatollah Khomeini returned from exile on February 1. Iran's military declared itself neutral on February 11, leading to rebel troops overwhelming troops loyal to the Shah in a widespread, violent street fight. Iran officially transformed from an absolute monarchy into an Islamic Republic with a strong majority vote on April 1, 1979. However, as with many political revolutions, this did not create a smooth transition - rival political groups fought over the writing of the new constitution and governance of Iran in the meantime. The Islamic Republican Party came to the forefront in these negotiations, which had a quick and extreme effect on the lives of women in the country who were forced to veil themselves again for the first time since Reza Shah's "unveiling" in 1936. At the same time, Iran was attacked by forces from its neighbor country Iraq in a fight over a border created during the resolution of World War I. From 1980-1988, Iraq and Iran were engaged in armed conflict, a war which led to many civilian deaths at the hands of Iraqi forces as well as the accusation and arrest of dissidents to the war on counts of treason. Since the late 80s and early 90s, a number of conservative leaders have controlled Iran by election, while reform movements, mostly championed by younger citizens, have slowly worked to change Iran's political, religious, and cultural environment.