https://en.m.wikipedia.org/wiki/Indo-European_migrations
https://en.m.wikipedia.org/wiki/Indo-Aryan_migration
https://en.m.wikipedia.org/wiki/Sintashta_culture
https://en.m.wikipedia.org/wiki/Historical_Vedic_religion
https://en.m.wikipedia.org/wiki/Mitra_(Vedic)
in Indo-Iranian (Vedic) Mitra means that which causes to bind, covenant, contract, oath. The protection of which is Mitra's role in both the "Rigveda" and in the "Mitanni Treaty".
https://en.m.wikipedia.org/wiki/Mitanni#Shattiwaza_/_Kurtiwaza
https://en.m.wikipedia.org/wiki/Mitanni-Aryan
The names of the Mitanni aristocracy frequently are of Indo-Aryan origin, and their deities also show Indo-Aryan roots..
(Mitra, Varuna, Indra)
https://en.m.wikipedia.org/wiki/Ṛta
https://en.m.wikipedia.org/wiki/Me_(mythology)