The doctrine of “Mahdi” has a long history among Muslims, especially Shi‘ites. Muslims have been familiar with the matter through Prophetic and Imams’ hadiths. Islamic sources contain many hadiths in which the Holy Prophet (S) and the Imams (A) have reported on the happening of the occultation and its relating issues, reports confirming that there will be that there will be two occultations for him, one of which will be longer than the other.
There are also many hadiths about this issue in Sunni sources. Based on these hadiths, as researchers have also mentioned, it can be claimed that the doctrine of Mahdi (A) has been one of the well-known, common and undeniable issues. Therefore, Shi‘ites would enter the “age of occultation” with a long-enough preparation and 260 years of history. The Shi‘ites’ knowledge of the doctrine of Mahdi did not only concern the heart of the matter but also included its features and details.