In other videos, we saw the first Crusades start at the end of the 11th century, started really by Pope Urban II with the purported reason to help the Byzantines take land from the Muslims, especially the Holy Land. The first Crusade is, for the most part, successful, but they don't return that land to the Byzantines. They set up what are known as Crusader States or Crusader Kingdoms, including the Kingdom of Jerusalem. And just to read this timeline that I drew up here, green shows the time period when at least Jerusalem is controlled by the Muslims. Red shows when Jerusalem is controlled by Western European powers or by these Crusader Kingdoms, which were essentially Western European. These red parts on our timeline show when the actual Crusades occurred. So you see the first Crusade causes the change of control of Jerusalem from the Muslims to the Western European Christians.