[This region is subject to] “a process of spiritualization of Avestan geography … in the famous celebration of the Hilmand in the Zamyad Yast…”, and … - Gherardo Gnoli

[the attempt to transpose the geography of the Avesta from Afghanistan to western Iran] “was doubtless due to different attempts made by the most powerful religious centres of western Iran and the influential order of the Magi to appropriate the traditions of Zoroastrianism that had flourished in the eastern territories of the plateau in far-off times. Without a doubt, the identification of Raya with Adurbadagan, more or less parallel with its identification with Ray, should be fitted into the vaster picture of the late location of Airyana Vaejah in Adarbayjan.” ...

These Aryas doubtless took with them their religious traditions as well, and this explains in what terms we must speak of the Achaemenians’ belonging to the airya tradition, i.e. to a religious and cultural heritage from a country further east. Afterwards Mazdeism grew up amongst them, and we do not know of any Mazdeism that could be defined for a certainty as non—Zoroastrian, nor, as I have tried to show elsewhere, have we any real reason, even if we take into account the name as—sa-ra ‘ma-za—as in the Assyrian tablets, to maintain that the very conception of a god such as Ahura Mazda was not the work of Zarathustra, in spite of the opinion of some leading scholars to the contrary and a hypothesis put forward recently by F.B.J. Kuiper. On the contrary, we might suppose that it was the decisive and most original feature of the message of the great prophet of ancient Iran’.

The only possible identification of Airyana Vaejah must point to the great Hindukus mountain range.