Humayun was defeated by Sher Shah Suri in 1540. He fled to the refuge of the powerful Safavid Empire in Persia. Shah Tahmasp, the ruler of Persia welcomed Humayun and treated him as a royal visitor. Shah Tahmasp urged Humayun to convert his religion from Sunni to Shia Islam. He accepted it to keep himself and several hundred followers alive. Shah Tahmasp promised him to provide his help to regain his kingdom.