His eldest son Abul-Kasim, who had twice led expeditions into Egypt, succeeded to the caliphate with the title of El-Kaim, 934-946.

But for the greater part of his reign El-Kaim was on the defensive, fighting for existence against the usurpation of one Abu-Yezid, who repudiated Shiism, cursed the Mahdi and his successor, stirred up most of Morocco and Barbary against El-Kaim, drove him out of his capital, and went near to putting an end to the Fatimite caliphate.

But for the greater part of his reign El-Kaim was on the defensive, fighting for existence against the usurpation of one Abu-Yezid, who repudiated Shiism, cursed the Mahdi and his successor, stirred up most of Morocco and Barbary against El-Kaim, drove him out of his capital, and went near to putting an end to the Fatimite caliphate.

The castle was built on a stony ridge of detritus called the Kaim, which stretches from Wark village towards Carham.