 The Umayyads actively discouraged conversion in order to continue the collection of the jizya, or the tax on non-Muslims.Islam nearly doubled within its territory from 8% of residents in 750 to 15% by the end of Al-Mansur's reign.Al-Mahdi, whose name means "Rightly-guided" or "Redeemer", was proclaimed caliph when his father was on his deathbed.