The Islamic Republic of Iran, home to one of the world's oldest civilizations, has played a significant role in both the Middle Eastern and Western geopolitical landscapes. Originally occupied by tribal peoples and later falling under control of the many empires that rose and fell within the region, Iran began a process of Islamization following its conquest by Arab caliphates during the 7th century. Although Iran would endure both foreign and domestic threats in the centuries to follow, it has remained a predominantly Muslim nation. A brief period of state-sponsored secularism followed the 1953 Iranian coup d'état, which was covertly backed by the English and American governments. However, this secular government was quickly deposed in the 1979 Iranian Revolution. In the wake of the Revolution, known today as the "Islamic Revolution," Iran held a referendum in which it was decided that the nation would officially become an Islamic Republic.