Zoroaster, also known as Zarathustra, is regarded as the spiritual founder of Zoroastrianism. He is said to have been an Iranian prophet who founded a religious movement that challenged the existing traditions of ancient Iranian religion, and inaugurated a movement that eventually became a staple religion in ancient Iran. He was a native speaker of Avestan and lived in the eastern part of the Iranian plateau, but his exact birthplace is uncertain. He founded the first documented monotheistic religion in the world and also had an impact on Plato, Pythagoras, and the Abrahamic religions – Judaism, Christianity, and Islam.
There is little scholarly consensus on when he lived. Some scholars, using linguistic and socio-cultural evidence, suggest a dating to somewhere in the second millennium BC. Other scholars date him to the 7th and 6th centuries BC as a near-contemporary of Cyrus the Great and Darius the Great. Zoroastrianism eventually became the official state religion of ancient Iran—particularly during the era of the Achaemenid Empire—and its distant subdivisions from around the 6th century BC until the 7th century AD, when the religion itself began to decline following the Arab-Muslim conquest of Iran. Zoroaster is credited with authorship of the as well as the , a series of hymns composed in his native Avestan dialect that comprise the core of Zoroastrian thinking. Little is known about Zoroaster; most of his life is known only from these scant 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 AD that historicizes legends and myths.
Name and etymology
Zoroaster's name in his native language, Avestan, was probably . His translated name, "Zoroaster", derives from a later (5th century BC) Greek transcription, (), as used in Xanthus's (Fragment 32) and in Plato's First Alcibiades (122a1). This form appears subsequently in the Latin , and, in later Greek orthographies, as . The Greek form of the name appears to be based on a phonetic transliteration or semantic substitution of Avestan with the Greek (literally 'undiluted') and the BMAC substrate with .
In Avestan, is generally accepted to derive from an Old Iranian ; The element half of the name () is thought to be the Indo-Iranian root for 'camel', with the entire name meaning 'he who can manage camels'. Reconstructions from later Iranian languages—particularly from the Middle Persian (300 BC) , which is the form that the name took in the 9th- to 12th-century Zoroastrian texts—suggest that might be a zero-grade form of . Subject then to whether derives from or from , several interpretations have been proposed.
If is the original form, it may mean 'with old/aging camels', related to Avestic (cf. Pashto and Ossetian , 'old'; Middle Persian , 'old'): 'with angry/furious camels': from Avestan , 'angry, furious'. 'who is driving camels' or 'who is fostering/cherishing camels': related to Avestan , 'to drag'. Mayrhofer (1977) proposed an etymology of 'who is desiring camels' or 'longing for camels' and related to Vedic Sanskrit , 'to like', and perhaps (though ambiguous) also to Avestan . 'with yellow camels': parallel to Younger Avestan .
The interpretation of the () in the Avestan was for a time itself subjected to heated debate because the is an irregular development: as a rule, (a first element that ends in a dental consonant) should have Avestan or as a development from it. Why this is not so for has not yet been determined. Notwithstanding the phonetic irregularity, that Avestan with its was linguistically an actual form is shown by later attestations reflecting the same basis. All present-day Iranian-language variants of his name derive from the Middle Iranian variants of , which, in turn, all reflect Avestan's fricative .
In Middle Persian, the name is , in Parthian , in Manichaean Middle Persian , in Early New Persian , and in modern (New Persian), the name is .