caliph

the civil and religious leader of a Muslim state considered to be a representative of Allah on earth; "many radical Muslims believe a Khalifah will unite all Islamic lands and people and subjugate the rest of the world"

उमर बिन खत्ताब के बाद उसमानरजी * बिन अफ्फान ६४४ में खलीफा बने।

Caliph is a title given to a religious muslim leader.