Zoroaster prophecy that saw a return of Sassanid emperor Bahram: Shoghi Effendi also stated that Zoroaster lived roughly 1000 years before Jesus. The Greeks—in the Hellenistic sense of the term—had an understanding of Zoroaster as expressed by Plutarch, Diogenes Laertius, and Agathias that saw him, at the core, to be the "prophet and founder of the religion of the Iranian peoples," Beck notes that "the rest was mostly fantasy". Zoroaster was set in the ancient past, six to seven millennia before the Common Era, and was described as a king of Bactria or a Babylonian (or teacher of Babylonians), and with
Zoroaster and Darius I. Zoroastrianism eventually became the official religion of Ancient Persia and its distant subdivisions from the 6th century BCE to the 7th century CE. Zoroaster is credited with authorship of the Gathas as well as the Yasna Haptanghaiti, hymns composed in his native dialect, Old Avestan, and which comprise the core of Zoroastrian thinking. Most of his life is known from these texts. By any modern standard of historiography, no evidence can place him into a fixed period, and the historicization surrounding him may be a part of a trend from before the 10th century that historicizes legends