Military collaboration between the Armenians and the Mongols began in 1258-1260, when Hethum I, Bohemond VI, and the Georgians combined forces with the Mongols under Hulagu in the Mongol invasion of Syria and Mesopotamia. In 1258, the combined forces conquered the center of the most powerful Islamic dynasty in existence at that time, that of the Abbasids in the siege of Baghdad. From there, the Mongol forces and their Christian allies conquered Muslim Syria, domain of the Ayyubid Dynasty. They took the city of Aleppo with the help of the Franks of Antioch, and on March 1, 1260, under the Christian general Kitbuqa, they also took Damascus.