Indo-Aryan Superstrate
Some theonyms, proper names and other terminology of the Mitanni exhibit close similarities to Indo-Aryan, 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, the deities Mitra, Varuna, Indra, and Nasatya (Ashvins) are invoked. Kikkuli's horse training text includes technical terms such as aika (eka, one), tera (tri, three), panza (pancha, five), satta (sapta, seven), na (nava, nine), vartana (vartana, turn, round in the horse race). The numeral aika "one" is of particular importance because it places the superstrate in the vicinity of Indo-Aryan proper as opposed to Indo-Iranian or early Iranian (which has "aiva") in general.
Another text has babru (babhru, brown), parita (palita, grey), and pinkara (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, the term for warrior in Sanskrit as well; note mišta-nnu (= miẓḍha,~ Sanskrit mīḍha) "payment (for catching a fugitive)" (M. Mayrhofer, Etymologisches Wörterbuch des Altindoarischen< Heidelberg 1986-2000; Vol. II 358).
Sanskritic interpretations of Mitanni royal 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 *tṷaiašaratha, Vedic Tvastr "whose chariot is vehement" (Mayrhofer, Etym. Wb., I 686, I 736).
Read more about this topic: Mitanni