This was the result of Ottoman conquests in the Levant, Arabia and North Africa having turned the empire from a multi-religious state to a state with a clear Muslim majority population, which necessitated a claim to legitimate political power rooted in Islamic rather than Roman tradition. The shift in Ottoman identity also resulted from conflict with the Safavid Empire in Iran, which followed Shia Islam, leading to the sultans more strongly embracing and stressing their Sunni Islam faith. Kayser-i Rûm was last used officially in the 18th century and Greek-language documents ceased to refer to the sultan as basileus at the latest in 1876, whereafter the Ottoman rulers were titled in Greek as soultanos and padisach.