 Isma'il, Dawud, and al-Mansur Ibrahim of Homs went to war with Ayyub, who hired the Khwarazmians to fight for him.The Khwarazmians were nomadic Turks from central Asia, who had recently been displaced by the Mongols further to the east and were now residing in Mesopotamia.With Ayyub's support they sacked Jerusalem in the summer of 1244, leaving it in ruins and useless to both Christians and Muslims.