Muhammad al-Mahdi

When Hasan al-Askari died in 873-874, possibly poisoned by the Abbasid caliphate, his main representative claimed the eleventh imam had left behind an infant son named Muhammad, kept secret to protect him from persecution. The child was said to have immediately entered occultation, accessible only through a series of four agents over seventy years - the Minor Occultation. In 940-941, the fourth deputy died after receiving a final letter announcing the beginning of the Major Occultation, a complete withdrawal that would last until Earth filled with tyranny and God permitted his return. The Shia community had fractured into rival sects over the succession, but within decades only the Twelvers survived, unified by belief in the hidden imam. By the tenth century, Twelver scholars formalized the doctrine: his life prolonged by miracle, the earth unable to exist without him as God's proof, leadership passing to jurists in his absence.