Who was in the crusades and where did they take place?

There were two sides to the crusades. The sides were the Muslim rulers of Jerusalem and the European Christians. Crusades took place across Europe, Asia, and the Middle East. The very first crusade took place in 1095. The pope at that time, pope Urban II, started the crusade.

 The crusades were mostly fought because the European Christians knew that the Muslims had settled on Palestine, which the Christians believed that it was their holy land. They believed the land was sacred because Jesus had walked upon the soil there. They also believed that Jerusalem was holy because that is the town where Jesus was crucified on the cross.