In early October 749 (132 AH), Abu al-'Abbās al-Saffāh's rebel army entered
Kufa, a major Muslim center in Southern
Iraq. Al-Saffah had not been yet declared caliph. One of his priorities was to eliminate his
Umayyad rival, caliph
Marwan II. The latter was defeated in February 750 at a battle on the
(Great) Zab river north of
Baghdad, effectively ending the Umayyad Caliphate, which had ruled since 661 CE. Marwan II fled back to
Damascus, which didn't welcome him, and was ultimately killed on the run in Egypt that August. Al-Saffah would go on to become the first Abbasid caliph, but he did not come forward to receive the pledge of allegiance from the people until after the Umayyad caliph and a large number of his princes were already killed. The only survivor,
Abd al-Rahman ibn Mu'awiya, escaped to the province of
al-Andalus (Spain), where the Umayyad dynasty would endure for three more centuries in the form of the
Emirate of Córdoba and the subsequent
Caliphate of Córdoba. Another version is that al-Saffāḥ's new governor to Syria,
'Abd Allāh ibn 'Ali, hunted down the last of the family dynasty, with only Abd al-Rahmān escaping. Ultimately, 'Abbasid rule was accepted even in Syria, and the beginning of the new Islamic dynasty was considered "free from major internal dissensions." Al-Saffāh's four-year reign was marked with efforts to consolidate and rebuild the caliphate. His supporters were represented in the new government, but apart from his policy toward the Umayyad family, al-Saffāh is widely viewed by historians as having been a mild victor.
Jews,
Nestorian Christians, and Persians were well represented in his government and in succeeding Abbasid administrations. Education was also encouraged, and the first
paper mills, staffed by skilled
Chinese prisoners captured at the
Battle of Talas, were set up in
Samarkand. Equally revolutionary was al-Saffāh's reform of the army, which came to include non-Muslims and non-Arabs in sharp contrast to the Umayyads who refused any soldiers of either type. Al-Saffāh selected the gifted
Abu Muslim as his military commander, an officer who would serve until 755 in the Abbasid army. Not all Muslims accept the legitimacy of his caliphate, however. According to later
Shi'ites, al-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 al-Saffāh's Shi'a supporters, although the continued amity of other groups made Abbasid rule markedly more solvent than that of the Umayyads. Caliph Abu al-ʿAbbās ʿAbd Allāh al-Saffāḥ died of
smallpox on 8 June 754 (13
Dhu'l-Hijja 136 AH), only four years after taking the title of caliph. Before he died, al-Saffah appointed his brother
Abu Ja'far al-Mansur and, following him, the caliph's nephew
Isa ibn Musa as his successors; ibn Musa, however, never filled the position. ==Abbasid military activities==