Byzantine Empire
A large number of people, known as the Turks, rode on horseback from Central Asia and attacked the Byzantine Empire. The Seljuk Empire took most of Anatolia from the Byzantines by 1091. However, they received help from people in Western Europe in what is known as the First Crusade. Many knights and soldiers left to help the Byzantines and to secure Jerusalem for the Christians. The city wad then controlled by the Muslims.