The Four Books
Prior to the rise of the Safavid Empire, Sunni Islam was the dominant religion, accounting for around 90% of the population at the time. According to Mortaza Motahhari the majority of Iranian scholars and masses remained Sunni until the time of the Safavids. The domination of Sunnis did not mean Shia were rootless in Iran. The writers of The Four Books of Shia were Iranian, as well as many other great Shia scholars.