The Mahdi will appear from the East. Even if mountains rise up before him he will crush and cross them, and he will find a path for himself in those mountains. (The Book of Portents of the Awaited Mahdi, p. 39)
Imam Mahdi (ra) will liberate those who are oppressed in the world...
Pray for the early appearance of Imam Mahdi (ra) and for us to be able to recognize him - Aameen
The concept of Mahdi is common between Sunnis and Shias, though the interpretations differ