The date of Zoroaster, or, the date of composition of the Old Avestan gathas, is unknown. Scholarly mainstream opinion mostly places him near the 1200 BC or 1100 BC, but dates proposed in scholarly literature diverge widely, between the 1800 BC and 6000BC.
"Enlightenment writers such as Voltaire promoted research into Zoroastrianism in the belief that it was a form of rational Deism, preferable to Christianity. With the translation of the Avesta by Abraham Anquetil-Duperron, Western scholarship of Zoroastrianism began"
Friedrich Nietzsche on Zoraster
On Zoroastian Traditions Customs and Ceremonies (By H.S. Spencer, Dastur K.S. Dabu)
Livius Zarathustra Livius Bactria
BALKH (BACTRIA) The Circle of Ancient Iranian Studies
from... http://www.bbc.co.uk/religion/religions/zoroastrian/history/zoroaster_1....
"The precise date of the founding of Zoroastrianism is uncertain. An approximate date of 1200-1500 BCE has been established through archaeological evidence and linguistic comparisons with the Hindu text, the Rig Veda."