information:classification, structural:expansion
Succession

After the death of Ja'far al-Sadiq, his following fractured, and the largest group, who came to be known as the Twelvers, followed his younger son, Musa al-Kadhim. It also appears that many expected the next Imam to be al-Sadiq's eldest son, Isma'il, who predeceased his father. This group, which later formed the Isma'ili branch, either believed that Isma'il was still alive or instead accepted the imamate of Isma'il's son, Muhammad. While the Twelvers and the Isma'ilis are the only extant Shia sects today, there were more factions at the time: Some followers of al-Sadiq accepted the imamate of his eldest surviving son, Abdullah al-Aftah. Several influential followers of al-Sadiq are recorded to have first followed Abdullah and then changed their allegiance to Musa. As Abdullah later died childless, the majority of his followers returned to Musa. A minority of al-Sadiq's followers joined his other son, Muhammad al-Dibaj, who led an unsuccessful uprising against Caliph al-Ma'mun, after which he abdicated and publicly confessed his error. A final group believed that al-Sadiq was not dead and would return as Mahdi, the promised savior in Islam.