Zengi, son of Aq Sunqur al-Hajib, became the Seljuk atabeg of Mosul in 1127. He quickly became the chief Turkic potentate in Northern Syria and Iraq, taking Aleppo from the squabbling Artuqids in 1128 and capturing the County of Edessa from the Crusaders after the siege of Edessa in 1144.