Ja'far ibn Abdallah al-Mansur

Ja'far ibn Abdallah al-Mansur (جعفر بن عبد الله المنصور) was the elder son of second Abbasid caliph al-Mansur and elder brother of third Abbasid caliph al-Mahdi. As the elder son of al-Mansur, he was the candidate to the caliphal throne until his premature death.

Life
Ja'far was the son of Abdallah ibn Muhammad al-Abbasi al-Hashimi (the future caliph al-Mansur) in 742/743. When Ja'far was eleven or twelve year old, his father became caliph.

His mother was Arwa. She was al-Mansur's first wife. Arwa also known as Umm Musa, whose lineage went back to the kings of Himyar. Her father was Mansur al-Himyari. She had a brother named Yazid.

Arwa had two sons, Muhammad (future Caliph al-Mahdi) and Ja'far. She died in 764. The two sons of Arwa, Ja'far and Muhammad were regarded as his heirs after the removal of Isa ibn Musa as heir. However Ja'far died during his father al-Mansur's reign. His brother, Muhammad became sole candidate to the throne.

One of his al-Mansur's concubines was a Kurdish woman. She was the mother of al-Mansur's son Ja'far. Al-Mansur named this son after his elder son.

After Ja'far's death, his father too care of his young children. When his father, al-Mansur died. His brother caliph al-Mahdi took the responsibility of his children. Al-Mahdi married his son and heir to Ja'far's daughter Zubaidah.

Relatives
Ja'far was related to several powerful figures of Abbasid House. He was the older brother of al-Mahdi and he was also maternal grandfather of al-Amin.

Jafar also had several half-siblings, After his mother's death, his father remarried and had children from his wives.