There are many views on the timeline of Zoroaster's life. Greek sources placed him as early as 6000 BC. The traditional Zoroastrian date for Zoroaster's birth and ministry is around 600 B.C. This is derived from a Greek source that places him "300 years before Alexander" which would give that date; other rationales for the 600 BC date identify the King Vishtaspa of Zarathushtra's Gathas with the father of the Persian King Darius, who lived around that time. According to the Zend Avesta, the sacred book of Zoroastrianism, Zoroaster was born in Azerbaijan, in northern Persia.
As the linguists of both Europe and India worked with the language of the Gathas attributed to Zarathushtra it became clear that they were far older than the language spoken in Iran at the time of King Darius' father. Gathic Avestan was very close to the Sanskrit of the Indian Rig-Vedas, which can be dated from the period 1500-1200 BC. This would mean that Zarathushtra lived far earlier than the "traditional" date. Some scholars have said that the 600 BC date is still plausible if Gathic Avestan was actually an artificially preserved sacred language, somewhat like Latin, which continued in literature and rituals thousands of years after it had ceased to be spoken.
Recent work by Martin Schwartz and Almut Hintze tends to discount this theory, as the linguists show that the Gathas are not the work of an academic writing in a dead language; they show all the signs of poetry composed and recited in an oral tradition, similar to the heroic poetry of Homer or the Rig-Vedas. These studies would confirm the earlier date for Zarathushtra.
Again, no one knows how Zarathushtra died, allegedly at age 77. Many legends and Zoroastrian tradition say that he was killed, while praying in the sanctuary, by a foreign enemy of the king. But there is no holiday commemorating the martyrdom of the Prophet, as there would be in other religions (Christianity, for instance) and other Zoroastrian traditions, and scholars, say that Zarathushtra died peacefully. His birthday is celebrated on March 21, as part of the Persian New Year Festival.
Ancient alien theorists believe Zarathustra was the son of an alien god named who went by the name Ahura Mazda in this scenario. Scholars believe Zoroaster was a priest and a prophet. Linked to the Magi, he was considered a magician. His spiritual influences have always affected human thought and reasoning; his goal, to show humans their connection to one source of light and consciousness.