In 1226, the crown was passed to rival Hethumids through Leo's daughter Isabella's second husband, Hethum I. As the Mongols conquered vast regions of Central Asia and the Middle East, Hethum and succeeding Hethumid rulers sought to create an Armeno-Mongol alliance against common Muslim foes, most notably the Mamluks. In the thirteenth and fourteenth centuries, the Crusader states and the Mongol Ilkhanate disintegrated, leaving the Armenian Kingdom without any regional allies. After relentless attacks by the Mamluks in Egypt in the fourteenth century, the Cilician Armenia of the Lusignan dynasty, mired in an internal religious conflict, finally fell in 1375.