eginning in 633 AD, Rashidun Arabs conquered Iran and largely displaced the indigenous faiths of Manichaeism and Zoroastrianism by Sunni Islam. Iran became a major contributor to the Islamic Golden Age that followed, producing many influential scientists, scholars, artists, and thinkers. The rise of the Safavid Dynasty in 1501 led to the establishment of Twelver Shia Islam as the official religion of Iran, marking one of the most important turning points in Iranian and Muslim history.[6][23] During the 18th century, Iran reached its greatest territorial extent since the Sassanid Empire, and under Nader Shah briefly possessed what was arguably the most powerful empire at the time.[24] Through the late 18th and 19th centuries, a series of conflicts with Russia led to significant territorial losses and the erosion of sovereignty.[25][26] Popular unrest culminated in the Persian Constitutional Revolution of 1906, which established a constitutional monarchy and the country's first legislative body, the Majles. Following a coup d'état instigated by the U.K. and the U.S. in 1953, Iran gradually became closely aligned with the United States and the rest of the West but grew increasingly autocratic.[27] Growing dissent against foreign influence and political repression led to the 1979 Revolution and the establishment of an Islamic republic.[16]
