The Crusades were a type of religious war in which Christians attempted to conquer the Holy Land. This region had long been dominated by Muslims.
The most successful of these Crusades was the first one, which resulted in the conquest of Jerusalem. Jerusalem was conquered after a siege which lasted from June 7 to July 15, 1099. After the siege, the Crusaders took the city. This led to several changes in Jerusalem. First, the conquest led to a widespread killing of Jews and Muslims, as the Crusaders attempted to kill every single inhabitant of the city. It also led to the establishment of the Kingdom of Jerusalem, which became the center from which Crusaders managed their holdings in the Holy Land. Jerusalem remained in the hands of Christians until 1187, after the Battle of Hattin.