 Al-Mahdi proclaimed that the caliph was the protector of Islam against heresy, and also claimed the ability to declare orthodoxy.Religious scholars averred that Al-Ma'mun was overstepping his bounds in the "Mihna", the Abbasid inquisition which he introduced in 833 four months before he died.The "Ulama" emerged as a force in Islamic politics during Al-Ma'mun's reign for opposing the inquisitions.