Zoroastrianism has been named so in the West because its prophet, Zarathustra, was known to the ancient Greeks as Zoroaster. He was an Iranian, and lived in what for his people was prehistoric times. It is impossible, therefore, to establish fixed dates for his life; but there is evidence to suggest that he flourished when the Stone Age was giving way for the Iranians to the Bronze Age, possibly, that is, between 1400 and 1200 B.C.
— Zoroastrians: Their Religious Beliefs and Practices
by Mary Boyce