The Occultation

The Occultation (Arabic: غيبة‎‎ Ghaybah) in Shia Islam refers to a belief that the messianic figure, or Mahdi, who in Shi'i thought is an infallible male descendant of the founder of Islam, Muhammad, was born but disappeared, and will one day return and fill the world with justice and peace. Some Shi'is, such as the Nizari Ismaili, do not believe in the idea of the Occultation. The groups that do believe in it differ on the succession of the Imamate, and therefore which individual is in Occultation. The Hidden Imam is still considered to be the Imam of the Time, to hold authority over the community, and to guide and protect individuals and the Shi'i community.

In Twelver Shia Islam, the largest branch of the Shia faith, twelfth imam, Muhammad al-Mahdi, went into Occultation in 874. The Occultation is split into the Minor Occultation and the Major Occultation. According to Shia, there are reasons for the Occultation: Imam being afraid of his being killed, not to be under the oath of tyrant rulers, the Shia are to be examined by God.

The Minor Occultation (Ghaybat al-Sughra) refers to the period when the Twelver Shia believe the Imam still maintained contact with his followers via deputies (Arab. an-nuwāb al-arbaʻa). During this period, from 874-941, the deputies represented him and acted as agents between him and his followers.

Shia believe that in 873, after the death of his father al-`Askari, the eleventh Imam, the 12th Imam was hidden from the authorities of the `Abbasid caliphate as a precaution. His whereabouts were disclosed only to a select few. Four close associates of his father became mediators known as Saf’ir, or between the Imam and his followers, until the year 941. This period is considered by Twelvers to be the first, or Minor Occultation (al-Ghayba).

...
Wikipedia