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 330 BCE. The Seleucid rulers who gained power following Alexander's death instituted an "Age of Alexander" as the new calendrical epoch. This did not appeal to the Zoroastrian priesthood who then attempted to establish an "Age of Zoroaster". To do so, they needed to establish when Zoroaster had lived, which they accomplished by (erroneous, some even identified Cyrus with Vishtaspa) counting back the length of successive generations, until they concluded that Zoroaster must have lived "258 years before Alexander". This estimate then re-appeared in the 9th- to 12th-century Arabic and Pahlavi texts of Zoroastrian tradition, like the 10th century Al-Masudi