When and where was Imam Mahdi born?
The last Imam of Shias and the 12th successor of the Messenger of God was born on Friday daybreak, on the 15th of Shaˈbān in 255 A.H. (868 A.D.) in Samarra (a town in Iraq). However, there is a disagreement about the exact year of his birthday. Some believe it was in 254 or, 256 A.H. It is also said that this difference could be due to the Imam’s birth taking place in secret.
All of Shias and some Sunnis believe that the Imam was born years ago and they regard it as a historical fact. Some of the scholars have referred to the words of some of these Sunni religious experts in their books.[1]
[1] You can refer to the book “Shia Shenāsī (to understand Shia) written by, Ali Asghar Rezwānī.”