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Some theonyms, proper names and other terminology of the Mitanni are considered to form (part of) an Indo-Aryan superstrate, suggesting that an Indo-Aryan elite imposed itself over the Hurrian population in the course of the Indo-Aryan expansion.
In a treaty between the Hittites and the Mitanni (between Suppiluliuma and Shattiwaza, c. 1380 BC), the deities Mitra, Varuna, Indra, and Nasatya ( Ashvins) are invoked. Kikkuli's horse training text (circa 1400 BC) includes technical terms such as aika ( Vedic Sanskrit eka, one), tera (tri, three), panza (pañca, five), satta (sapta, seven), na (nava, nine), vartana (vartana, round). The numeral aika "one" is of particular importance because it places the superstrate in the vicinity of Indo-Aryan proper ( Vedic Sanskrit eka, with regular contraction of /ai/ to [eː]) as opposed to Indo-Iranian or early Iranian (which has *aiva; compare Vedic eva "only") in general.
Another text has babru(-nnu) (babhru, brown), parita(-nnu) (palita, grey), and pinkara(-nnu) (pingala, red). Their chief festival was the celebration of the solstice (vishuva) which was common in most cultures in the ancient world. The Mitanni warriors were called marya (Hurrian: maria-nnu), the term for (young) warrior in Sanskrit as well; note mišta-nnu (= miẓḍha,~ Sanskrit mīḍha) "payment (for catching a fugitive)" (Mayrhofer II 358).
Sanskritic interpretations of Mitanni names render Artashumara (artaššumara) as Arta-smara "who thinks of Arta/Ṛta" (Mayrhofer II 780), Biridashva (biridašṷa, biriiašṷa) as Prītāśva "whose horse is dear" (Mayrhofer II 182), Priyamazda (priiamazda) as Priyamedha "whose wisdom is dear" (Mayrhofer II 189, II378), Citrarata as citraratha "whose chariot is shining" (Mayrhofer I 553), Indaruda/Endaruta as Indrota "helped by Indra" (Mayrhofer I 134), Shativaza (šattiṷaza) as Sātivāja "winning the race price" (Mayrhofer II 540, 696), Šubandhu as Subandhu 'having good relatives" (a name in Palestine, Mayrhofer II 209, 735), Tushratta (tṷišeratta, tušratta, etc.) as *tṷaišaratha, Vedic Tveṣaratha "whose chariot is vehement" (Mayrhofer I 686, I 736).
Archaeologists have attested a striking parallel in the spread to Syria of a distinct pottery type associated with what they call the Kura-Araxes culture.