Not all Muslims accept the legitimacy of his caliphate, however. According to later Shi'ites, as-Saffāh turned back on his promises to the partisans of the Alids in claiming the title caliph for himself. The Shi'a had hoped that their "imam" would be named head of the caliphate, inaugurating the era of peace and prosperity the millennialists had believed would come. The betrayal alienated as-Saffāh's Shi'a supporters, although the continued amity of other groups made Abbasid rule markedly more solvent than that of the Umayyads.