Abu al-Abbas 1st Abbasid Calif r. 750-754

Abbas al-Saffaḥ - أبو العباس عبد الله بن محمد السفّاح

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After Muhammad ibn al-Hanafiyya died, his son Abu Hashim claimed the imamate. After his death the Abbasids claimed that on his deathbed Abu Hashim nominated his distant cousin Muhammad ibn Ali ibn Abdullah ibn Abbas ibn Abdu'l-Muttalib ibn Hashim as the imam. This man's son Abu'l-Abbas Abdullah as-Saffah became the first Abbasid caliph, repudiating Shi'ism, which effectively extinguished the sect that had recognized Muhammad ibn al-Hanafiyyah as an imam.[9] https://www.wikiwand.com/en/Muhammad_ibn_al-Hanafiyyah

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[After the death of Husayn, there were three different lines of Alids which compteted for allegiance of the legitimist faction: Those descended from Hasan and Husayn, the two sons of Ali by his wife Fatima, the daughter of the Prophet who left no son and the House of Muhammad, the son of Ali by another wife known as the Hanifite.... The first Alid faction to become prominent was the partisans of Muhammad, the son of the Hanifite Muhammad bin al-Hanafiyya , who were formed into a society by Kaysan, a freedman of Ali, for the purpose of avenging Hasan and Husayn, Ali's sons by Fatima. At Muhammad's death (AH 81), the Kaysanites recognized his son Abu Hashim as the 5th Imam until AH 98 when Abu Hashim died childless after bequeathing his claims to Muhammad b. Ali b. Abdullah (d.126) Muhammad ibn Ali ibn Abd Allah of the Quraysh tribe who was not of the House of Ali at all and who became the founder of the Abbasid dynasty which obtained the Khalifate in 132 AH (749) ...] ref:p. 9 of A Short History of The Fatimid Khalifate by Lacy O'Leary, lecturer in Aramaic and Syriac, Bristol University.

https://www.wikiwand.com/en/List_of_Abbasid_caliphs

1st Caliph of the Abbasid Caliphate

Reign 750 – 10 June 754

Predecessor Dynasty established
Marwan II as Umayyad Caliph

Successor al-Mansur

Spouse Umm Salamah bint al-Makhzum

Issue Raitah bint As-Saffah

Full name Kunya: Abul-Abbas

Given name: Abdullah

Laqab: as-Saffah

Nasab: Abdullah ibn Muhammad ibn Ali ibn Abdullah ibn Abbas ibn Abdul Muttalib ibn Hashim

Father Muhammad

Mother Raita Al-Harsia

In early October 749 (132 AH), Abu al-'Abbās as-Saffāh's rebel army entered Kufa, a major Muslim center in Southern Iraq, and as-Saffah was not really declared caliph. His first or maybe second or third priority 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 AD. Marwan II fled back to Damascus, which didn't welcome him, and was ultimately killed on the run in Egypt that August.[4]

In one far-reaching, historic decision, as-Saffāh established Kufa as the new capital of the caliphate, ending the dominance of Damascus in the Islamic political world, and Iraq would now become the seat of 'Abbassid power for many centuries.