Much of what is now southern Russia and Ukraine was once dominated by Iranian tribes--Scythians, Sarmatians, Alans. In modern times, all that is left of them are the Ossetians. (At least that's all that is left linguistically--of course some East Slavs may be descended in part from Slavified Iranian-speakers.) Is there any plausible way to have a much larger Iranian presence in Russia and Ukraine lasting into modern times?