"The answer is Caliphate.The territory of a caliph is called a caliphate. Caliphate is an Islamic area which is believed to be the residence of the Caliph. Caliph is a person that is believed to be the religious successor of Prophet Mohammad."
I believe the best answer is C if I say so
Between the Christian European states and the Islamic states of the Middle East and Africa. This has commonly been also known as the Crusades which started around the 10th century in the Middle east and have continued for a couple of centuries before losing their momentum.