Twelver doctrine holds that the twelfth Imam, Muhammad al-Mahdi, went into hiding as a young child around 874 to escape persecution, entering what is termed the Minor Occultation, during which he is held to have communicated with the Shia community through four successive deputies. In 941, with the death of the fourth deputy, the Major Occultation began, understood as continuing to the present: the twelfth Imam is believed to remain alive, hidden by divine power, and will return as the Mahdi to establish justice before the end of the world, a belief with parallels in eschatological expectations across other religious traditions but distinctive in its specific historical figure and unbroken genealogical claim.
Because the Imam is in occultation, Twelver Shia religious authority in the interim is exercised by senior clerical scholars called marja, whose rulings on law and doctrine believers may choose to follow. This arrangement, formalized over centuries and most systematically in the concept of wilayat al-faqih, guardianship of the jurist, developed by Ayatollah Ruhollah Khomeini in the twentieth century, gives Twelver Shia religious governance a structure of scholarly authority operating explicitly as a placeholder for, rather than a replacement of, the hidden Imam's own authority.