Due to Twelve Caliphs (pbu th) [12 Shiites’ imams)

Shiites – and also Sunnis – believe that prophet Muhamad (pbuh&h) declared the survival and dignity of Islam until the Day of Judgment, due the twelve caliphs

Sunnis have been unable to introduce these people, but in Shiites’ teaching, these twelve divine caliphs have been known and specified.
By investigation of their life history an individual can see, the birth of God’s last proof [imam Mahdi (pbuh)] _like prophets Abraham and Moses (pbu th)_ happened secretly, because of “the pressure of oppressive regimes”
This kind of birth was along with some doubts, so most of the Sunnis deny that honorable imam’s birth.

Shia scholars have compiled many books till now, to prove his birth…