There is no scholarly consensus on when he lived. However, approximating using linguistic and socio-cultural evidence allows for dating to somewhere in the second millennium BCE. This is done by estimating the period in which the Old Avestan language (as well as the earlier Proto-Indo-Iranian and Proto-Iranian languages and the related Vedic Sanskrit) were spoken, the period in which the Proto-Indo-Iranian religion was practiced, and correlation between the burial practice described in the Gathas with the archeological Yaz culture. However, other scholars still date him in the 7th and 6th century BCE as a near-contemporary of Cyrus the Great and Darius I. Zoroastrianism eventually became the official religion of Ancient Persia and its distant subdivisions from the 6th century BCE to the 7th century CE. Zoroaster is credited with authorship of the Gathas as well as the Yasna Haptanghaiti, hymns composed in his native dialect, Old Avestan, and which comprise the core of Zoroastrian thinking. Most of his life is known from these 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 that historicizes legends and myths.
If Zarantuštra is the original form, it may mean "with old/aging camels",  related to Avestic zarant-  ( cf. Pashto zōṛ and Ossetian zœrond , "old"; Middle Persian zāl , "old"):