A major Shīʿī Muslim community, the Ismāʿīlīs have had a long and eventful history dating back to the formative period of Islam, when different communities of interpretation were developing their doctrinal positions. The varying viewpoints of the then nascent Muslim community (umma) on certain central theological issues and the question of leadership after the Prophet Muḥammad were eventually elaborated in terms of what became known as the Sunnī and Shīʿī interpretations of the Islamic message. The Shīʿa themselves, upholding a particular conception of leadership and religious authority in the community, were further subdivided into a number of communities and smaller groups or sects. This was not only because they disagreed over who was to be their rightful spiritual leader or imam from amongst the Prophet's family, the ahl al-bayt, but also because divergent trends of thought and policy were involved.

By the time of the ʿAbbāsid revolution in 132/750, Imāmī Shīʿism, the common heritage of the major Shīʿī communities of the Ithnāʿashariyya (or Twelvers) and the Ismāʿīliyya, had acquired a special prominence under the leadership of Jaʿfar al-Ṣādiq, their ʿAlid imam. The Imāmī Shīʿīs, who like other Shīʿī groups upheld the rights of the ahl al-bayt to the leadership of the Muslims, propounded a particular conception of divinely instituted religious authority, also recognizing certain descendants of the Prophet's family from amongst the ʿAlids, the progeny of the Prophet's cousin and son-in-law ʿAlī b. Abī Ṭālib, as their imams possessing the required religious authority.