Dating Zarathushtra and the Rig Veda

Hi Folks

The best I have been able to dig out on the dating of Zarathushtra is
as follows

The earliest Greek sources give very early dates. Xanthos of Lydia
for instance gives 600 (or 6,000?) years before Xerxes. Other
ancient
Greeks are even more extravagant. It would seem that this is an
ayyempt similar to that of the Jews, who when they came into contact
with the Babylonian civilisation so much older than their own tried
to
invent truly ancient traditions out of rivalry with those of old
Mesopotamia.

Later Zoroastrian tradition, followed by Muslims such as al-Biruni,
give a date of 258 years perior to the accession of Alexander from
Darius III in 330 BCE. This date, said to be in Zarathushtra's 42nd
year, marks the conversion of King Vishtaspa to the new faith. Thus
the Zoroastrian religion may be said to date from 588 BCE, with
Zarathushra born 670BCE and died when he was 77 in 553 BCE. Richard
Frye gives a range from 628-551 BCE for the life of Zarathushtra.

This would make him firmly of Karl Jaspers' Axial age, a rough
contemporary of Isaiah, the early Greek Sophists, Siddhartha and Gung
fu Dze (Master Confucius) (what a meeting that could have been!).
Thus rather than contemporaneous with the Rig Veda, the earliest
Gathas would have been at roughly the same time as the ealiest
parts pf the Pala Canon on Buddhism.

Has someone got access to similar datings for the Rig Veda?

Hope this helps

John