Would these Cults sound good for a Horror series?

Why not just make the desert nomads to just nomads since most Persians were steppe nomads and saracens into something bit less Arabic like Magi since saracen was usually a lable for Arabs only and not Persians. Change necromancy into mysticism or something else or scrap the cult of Ostanes altogether because the Persians are not known at all for necromancy but the Magi of Persia were rumored to be mystics.