The Persian Empire is well documented in history.
Persia began as the tribal area of Persis, which we know of now as the area of Fars, in the southwestern corner of Iran. Iran, as a country now, is only a fraction of what the Persian Empire became. However when Persia is mentioned in Bible prophecy, it seems to explain the region we know of now as Iran – the land of the Aryans! Even as it expanded into Elam, Media and up into what is now Azerbaijan, (from the Gulf to the Caspian Sea) it still only explains the western side of Iran.