European attitudes began to change in the mid-1260s, from perceiving the Mongols as enemies to be feared, to potential allies against the Muslims. The Mongols sought to capitalize on this, promising a re-conquered Jerusalem to the Europeans in return for cooperation. Attempts to cement an alliance continued through negotiations with many leaders of the Mongol Ilkhanate in Persia, from its founder Hulagu through his descendants Abaqa, Arghun, Ghazan, and Öljaitü, but without success. The Mongols invaded Syria several times between 1281 and 1312, sometimes in attempts at joint operations with the Franks, but the considerable logistical difficulties involved meant that forces would arrive months apart, never able to coordinate activities in any effective way. The Mongol Empire eventually dissolved into civil war, and the Egyptian Mamluks successfully recaptured all of Palestine and Syria from the Crusaders. After the Fall of Acre in 1291, the remaining Crusaders retreated to the island of Cyprus. They made a final attempt to establish a bridgehead at the small island of Ruad off the coast of Tortosa, again in an attempt to coordinate military action with the Mongols, but the plan failed, and the Muslims responded by besieging the island. With the Fall of Ruad in 1302, the Crusaders lost their last foothold in the Holy Land.