The pre-Zoroastrian religion of the Iranians was a local variant of Vedic Hinduism. Zoroaster came in and was somewhat of a reformer, bringing in monotheism. Suppose Zoroaster is never born, or his beliefs never gain ang ground. What becomss of the Persian, Medes, Bactrians? Are they lumped into the Indian cultural sphere of do they still develop their own identity due to their proximity to Mesopotamia? How does that affect their influence on the Greeks? Does Judaism still develop a strong monotheistic belief? Are the other Abrahamic faiths greatly different from OTL, or butterflied away completely?