[the Avesta reflects] “an historical situation in which Iranian elements exist side by side with … Aryan or Proto-Indoaryan (elements)”. ... - Gherardo Gnoli

The foregoing leads us to believe that the answer which we gave earlier, at the beginning of this chapter, to the question as to whether we ought to see a sort of continuity and a close link between the western Aryas, the Medes and the Persians and the Airyas of the Avestan people, is a well grounded one. We can reply that the Aryas who became part of the ethnic groups of the Medes and the Persians were none other than western branches of the Avestan Airyas who, in their westward migrations, had taken with them the name Aryan and so had extended, in a way, the boundaries of Ariana proper.

“in the denomination of Ariana, which became known to the Greeks after the Macedonian conquest of the eastern territories of the old Persian empire, there was obviously reflected a tradition that located the Aryan region in the central-southern part of eastern Iran, roughly from the Hindukus southwards, and that considered some of the Medes and the Persians in the west and some of the Bactrians and Sogdians in the north as further extensions of those people who were henceforth known by the name of Ariani. And this, to tell the truth, fits nicely into the picture we have been trying to piece so far. Here too, as in the passages of the Avesta we have studied from the Mihr Yast and the Zamyad Yast, the geographical horizon is central-eastern and southeastern; the northern lands are also completely peripheral, and Chorasmia, which is present only in the very peculiar position of which we have spoken in the Mihr Yast, is not included.” ...

The Hilmand region and the Hamun-i Hilmand are beyond all doubt the most minutely described countries in Avestan geography. ...