One of the reasons for the Crusaders' victories was that the Muslims were in a state of disorder after the Turkish takeover. Ironically, this was the converse of the situation which had brought the Muslims to power centuries before (during the 600's), when they seized most of the Middle East. Back then, the Persians and Byzantines were exhausted by war, and the Muslims had taken advantage of that to establish themselves in power. Several centuries later, the Crusaders' conquest of the Holy Lands surely looked to some like reciprocity.