The Umayyad Caliphate ruled over a vast multiethnic and multicultural population. Christians, who still constituted a majority of the caliphate's population, and Jews were allowed to practice their own religion but had to pay a head tax (the jizya) from which Muslims were exempt. There was, however, the Muslim-only zakat tax, which was earmarked explicitly for various welfare programmes. Prominent positions were held by Christians, some of whom belonged to families that had served in Byzantine governments. The employment of Christians was part of a broader policy of religious accommodation that was necessitated by the presence of large Christian populations in the conquered provinces, as in Syria. This policy also boosted Muawiya's popularity and solidified Syria as his power base.