Was Zoroaster a Hindu?
Pre-Zoroastrian Paganism (Daevayasna) was the Persian religion prior to Zarathustra. Zarathustra`s religion Mazdayasna was it`s rival. It is all rather complicated because the Deva/Daeva thing gets reversed and so on. The Hindu religion could have come from either source, but most likely from Daevayasna.