Why did Muslim people in the Middle East and other parts of Asia experience hardship during the time of the European Middle Ages?

A.
They were repeatedly invaded and conquered by Mongol armies from central Asia.

B.
Byzantine Christians forced their religion on Muslim people throughout the region.

C.
Their leaders, Muslim nobles, forced most Muslims to be serfs.

D.
Western European crusaders conquered the Muslim empires and enslaved most of the people.