The history and doctrine of The Twelvers or Ithna asharis, who would become the predominant Shia community believing in a line of twelve (Arabic, ithnaʿashar) imams, evolved out of the earlier Imami Shiism as it had been consolidated by Imam Jaʿfar al-Sadiq. This branch of Shiism is of high significance among all Shia branches which were introduced briefly in the previous post.
The main doctrine of Imami Shiism
The Imami doctrine of the imamate, emphasizing the necessity of the earthly presence of an imam at all times, had equipped the Imami Shias of the 2nd/8th century with their central teaching. Subsequently, the Imami Shias themselves gradually split into various groups.
However, it was not until the middle of the 4th/10th century that one of the then developing Imami Shiʿi groups acquired the distinctive designation of Twelvers.
Ithan Ashari doctrine of Shiism:
The particular Imami Shiis who had become known as Twelvers were then characterized by their upholding of the doctrine of the twelve imams, starting with ʿAli b. Abi Talib and ending with Muhammad b. al-Hasan, acknowledged as the eschatological Mahdi who was in hiding and whose reappearance (rajʿa) was awaited by the members of his Shia community. Thus, it took more than a century after the death of Imam al-Sadiq for the doctrine of the twelve imams to be crystallized.
Ithna Ashari Imams:
The imamate period and then death of the sixth Shia imam, is a turning point in the the history and doctrine of the Twelvers or Ithna asharis.
On his death in 148/765, his succession was disputed an simultaneously claimed by three of his sons, ʿAbd Allah al-Aftah, Musa al-Kazim and Muhammad al-Dibaj.
Musa al-Kazim, later counted as the seventh imam of the Twelvers . On Musa al-Kazim’s death his Imami Shii following split into several sects. One large group denied his death and held that he would return as the Mahdi. However, another significant group of Musa al-Kazim’s followers now acknowledged his son ʿAli as their next imam, later counted as the eighth imam of the Twelvers.
One group recognized his only son, Muhammad b. ʿAli, known by the titles al-Jawad and al-Taqi, who was then seven years of age, as their imam. However, Muhammad al-Jawad, counted as the ninth imam of the Twelvers.
The majority of Muhammad al-Jawad’s Imami followers then acknowledged the imamate of his son ʿAli b. Muhammad, who would carry the epithets al-Hadi and al-Naqi. On ʿAli al-Hadi’s death, the majority of his partisans acknowledged his son al-Hasan as their next imam.
Upon the death of al-Hasan al-ʿAskari, his Imami partisans, who by then constituted a large and expanding community in several regions, faced a serious crisis of succession as the deceased imam had left no manifest heir. In Shiʿi tradition this phase of their history is referred to as a period of confusion (hayra) lasting several decades before it was resolved doctrinally. In the event, the Imami Shiis split into more than a dozen groups, of which only one (the Imamiyya proper) was to survive as the Twelver Shia.
However, a main group, later designated as the Ithna ashari or Twelvers, soon came to hold that a son named Muhammad had been born to Imam al-ʿAskari in 255/869, five years before his death. They further held that the child, who had received his father’s designation as his successor, had been kept hidden from the beginning, though his existence had been divulged to a few trusted associates of the imam.
According to this Imami tradition, Muhammad succeeded his father to the imamate in due course in 260/874, while remaining in occultation as before. It seems that, initially, at least some of these Imamis expected Muhammad to reappear and take charge of the communal affairs, also holding that the imamate would then continue through his progeny. However, before long, the Imamis identified their hidden imam with the eschatological Mahdi and its equivalent the qaʾim (the ‘riser’), and ended their line.
Taken from: A History of Shiʿi Islam
By: Farhad Daftary