According to the perspective of Shiite, Imam Mahdi (a.j.) (another name: Imam Zaman) will reappear as the last Imam of Shiite to save the world from the oppression. I'd like to know what will precisely occur. Actually I mean will the world be finished after a short and limited time (by governorship of him)? (As a world which would be without any oppression)
Or the world is going to begin a new and long period of life that won't be clear when it is going to be finished? (Sunni view)
Note: On the whole, I am looking for Sunni view about the mentioned issue, even though they agree the matter by another name (except Mahdi) as the savior of the world. (Perhaps some or many of them agree with the name of Mahdi as well).