As the title says above, is there a way for Buddhism to become the dominant, or at the very least, a strong minority religion in Persia?
Of course, I suck at creating TL's, but one possibility I could imagine is if say, the Zorastrian Empire collapses due to internal struggle, rather than at the behest of the Muslims, it could be the White Huns who take advantage of the chaos to implement their religious beliefs. To be quite certain, I don't know much about Persia in late antiquity, or the status of Buddhism for that matter, but I just wanted to state the possibility.