Each of the city-states of the Fertile Crescent was ruled by its own emir, whether as an independent potentate or as the subordinate or ally of a wider dynasty or federation. Imad ad-Din Zengi established dominance over the ‘Fertile Crescent’ from Mosul to Aleppo. His son Nur ad-Din, ruler of Aleppo, achieved lordship over Damascus and, through his Kurdish general Shirkuh, control of Egypt. However, it was Sirkhuh’s nephew Salah al-Din who brought the combined emirates’ power to bear on the Crusader States, crippling the kingdom of Jerusalem in 1187.