The Safavid conversion of Iran to Shia Islam was a process that took place roughly over the 16th through 18th centuries and turned Iran, which previously had a Sunni majority, into the spiritual bastion of Shia Islam. It was a process that involved forced conversion and resulted in hostility with Iran's Sunni neighbours. The conversion also ensured the dominance of the Twelver sect within Shiism over the Zaidiyyah and sects of Isma'ilism – each of whom had previously experienced their own eras of dominance within Shiism. Through their actions, the Safavids reunified Iran as an independent state in 1501 and established Twelver Shiism as the official religion of their empire, marking one of the most important turning points in the history of Islam.