Zoroaster

Zoroaster, also known as Zarathustra, was a religious reformer and the spiritual founder of Zoroastrianism. He founded the first documented monotheistic religion in the world and also had an impact on Plato, Pythagoras, and the Abrahamic religions, including Judaism, Christianity, and Islam. Zoroastrians believe that he was a prophet who transmitted God's messages and founded a religious movement that challenged the existing traditions of ancient Iranian religion, while in the minority Ahmadiyya branch of Islam and in the Baháʼí Faith, he is also considered a prophet. He was a native speaker of Avestan and lived in the eastern part of the Iranian plateau, but his exact birthplace is uncertain.

Most scholars, using linguistic and socio-cultural evidence, suggest a dating to somewhere in the second millennium BC. 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 Gathas as well as the Yasna Haptanghaiti, a series of hymns composed in his native Avestan dialect that compose 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.