The Mongol Empire's westward expansion reached the Middle East when the Mongols conquered the Khwarazmian Empire in Central Asia in 1227. Part of the Khwarazmian army fled to eastern Anatolia and these masterless Turkic soldiers offered their services to the neighbouring rulers for pay. Western Christians regarded the Mongols as potential allies against the Muslims because some Mongol tribes adhered to Nestorian Christianity. In fact, most Mongols were pagans with a strong belief in their Great Khan's divine right to universal rule, and they demanded unconditional submission from both Christians and Muslims. As-Salih Ayyub hired the Khwarazmians and garrisoned new troops in Egypt, alarming his uncle As-Salih Ismail, Emir of Damascus. Ismail bought the Franks' alliance by a promise to restore 'all the lands that Saladin had reconquered'. Catholic priests took possession of the Dome of the Rock, but in July 1244 Khwarazmians marching towards Egypt sacked Jerusalem unexpectedly. The Franks gathered all available troops and joined Ismail near Gaza, but the Khwarazmians with the Egyptians defeated the Frankish and Damascene coalition at La Forbie on 18 October. Few Franks escaped from the battlefield. As-Salah captured most of the crusaders' mainland territory restricting the Franks to a few coastal towns. Louis IX of France launched a failed crusade against Egypt in 1249. He was captured near Damietta with the remnants of his army, and ransomed days after the Bahri Mamluks assumed power in Egypt through murdering As-Salih's son Al-Muazzam Turanshah in May 1250. Louis spent four more years in Outremer. As the kingdom's effective ruler, he conducted negotiations with both the Syrian Ayyubids and the Egyptian Mamluks and refortified the coastal towns. He sent an embassy from Acre to the Great Khan Güyük, offering an anti-Muslim alliance to the Mongols.