In Achaemenid studies, Wouter Henkelman’s book The Other Gods Who Are is famous for using some very difficult sources to argue that we should not think about Iranians replacing and subjugating Elamites, but that the ancient Persians we know were the product of hundreds of years of interaction between Iranian-speakers and Elamite-speakers sharing the highlands of Fars, so that by the time of Cyrus or Darius it was hard to say what was Iranian and what was Elamite. Elam had traditionally included both lowland Susa and highland Anšan, and by the time of Cyrus the difference between mountain and plain may have felt more real than any difference in language or religion inside one region.
As this study aims to show, the religious landscape of the Achaemenid heartland was a fascinating and variegated tapestry woven from Elamite and (Indo-)Iranian traits. It will be argued that, though heterogeneous, this landscape was nevertheless a unity that was treated as such by the administrators at Persepolis. ‘Iranian’ and ‘Elamite’ cults were not only treated alike, but were actually not separated in clearly distinct sections. The gods venerated and the cults sponsored were only so because they were considered to be Persian, i.e. as belonging to the rich intercultural milieu of first-millennium Fārs. (p. 58)
As I take my first glance through it, I find that it has other treasures:
One question that arises at this point is whether [the hoard of silverware from] Kalmākarra is an exception, or an indication of the overall level of prosperity in the period under discussion [ie. the century after the Assyrian invasions around 640 BCE]. Confirmation of the thesis that ‘Kalmākarra’ is not an exceptional case is the rich inventory of a stone burial chamber, discovered by chance in 1982 at Arǧān near Behbahān in eastern Khūzestān. The funerary deposits, in and outside of a bronze coffin, included an elaborate bronze stand (or ‘candelabrum’), a large gold ceremonial object (‘ring’), a dagger decorated with precious stones and gold filigree, a silver rod, a bronze lion beaker and a large bowl with engraved scenes. Four of the objects have an Elamite inscription reading “Kidin-Hutran, son of Kurluš.” Apart from metal objects, the tomb also contained remains of embroidered garments. The 98 gold bracteates, also found in the coffin, may have been sewn to one or several of these garments. There is now a communis opinio on the tomb’s date: the later seventh or early sixth century BC (i.e. contemporaneous with the Kalmākarra hoard and the Acropole texts). The Arǧān find is of major importance for its international context. The tomb inventory displays a range of different styles and iconographic themes (Phoenician, Syrian, Elamite, Assyrian) and some objects probably reached Kidin-Hutran via long-distance trade. This is particularly true for the textiles found in the tomb, at least three of which are made of cotton – these are, in fact,among the earliest Near Eastern examples of cotton garments. As Javier Álvarez-Mon argues, maritime trade between Elam and Dilmun, where cotton was grown in this period, is the most likely source of the fabric or the raw material (Álvarez-Mon [forthc. 1]).
Besides the regional network described above, there is some evidence for relations that involve longer distances. An Acropole text (s 158 rev.5-6) attests to exchanges with the “king of the Egyptians” ( BE EŠŠANA AŠ mi-iz-ri-[ib-be-]na). There is also some evidence for Elamite-Urartean trade and perhaps political contacts.
– Wouter Henkelman, The Other Gods Who Are, Achaemenid History XIV, pp. 30, 31, 48 https://archive.org/details/WouterHenkelman.theOtherGodsWhoAre
Henkelman thinks that the domestication of the camel opened new trade routes through the Syrian desert, like those which later made Palmyra rich. Dilmun is a very old and traditional name, but in earlier periods it referred to somewhere in the Persian gulf where merchants from Mesopotamia met visitors from distant lands. In the third millennium BCE, cities in southern Mesopotamia had been trading through Dilmun with Maka and Meluhha (somewhere around the Indus Valley?) In the second millennium, however, that trade seems to have been interrupted (perhaps something to do with whatever happened to the Harappans?) I did not know that through all the thundering and righteous violence of the Assyrian kings, those old trade routes had come back into use.