In 756, Abd al-Rahman I, a prince of the deposed Umayyad royal family, refused to recognize the authority of the Abbasid Caliphate and became an independent emir of Córdoba. He had been on the run for six years after the Umayyads had lost the position of caliph in Damascus in 750 to the Abbasids. Intent on regaining a position of power, he defeated the existing Muslim rulers of the area who had defied Umayyad rule and united various local fiefdoms into an emirate. However, this first unification of al-Andalus under Abd al-Rahman still took more than twenty-five years to complete (Toledo, Zaragoza, Pamplona, Barcelona).

For the next century and a half, his descendants continued as emirs of Córdoba, with nominal control over the rest of al-Andalus and sometimes even parts of western Maghreb, but with real control always in question, particularly over the marches along the Christian border, their power vacillating depending on the competence of the individual emir. For example, the power of emir Abdullah ibn Muhammad al-Umawi (c. 900) did not extend beyond Córdoba itself.