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