As we know, the history of Christian Orthodox Russia began with the conversion of Vladimir of Kiev and of its people.
This marked russian identity forever, and they called themselves the Third Rome after Byzantium fell to the Ottomans.
Is it feasible to have the same (a marginal political entity that organizes and conquer all of Siberia as gunpowder gets around) happening for, say, a surviving Persian Empire that manages to convert some newly settled Turks to its religion (Zoroastrism or Nestorianism)?
I'm thinking about the region East of the Caspian sea, or even around Samarkand. Or, if we want an even fancier ATL, we can convert some slavs/turks that wander over the Caucasus. Zoroastrian Russians seem cool.
So, my questions are:
-What was the "official policy" of the Sassanids against "barbarian" (less organized) tribes? Did they try to convert them/settle them/use them as mercenaries?
-From what i heard, the Persian Empire's élites was a landed one, unlike in the ERE. Could this have hampered an urban tradition that usually goes hand in hand with Christianity? In other words, was Christianity (and its institutions, with bishops and all) more suited to the development of barbarian tribes than Zoroastrism was?
-Regarding the second question: what did Sassanid use to strenghten their Empire? Romans (until Late antiquity) used religion/orthodoxy and urban tradition, but what about the Persians?
Thanks in advance.