The origin of the Vedic civilization and its relation to
the Indus Valley civilization, Indo-Aryan migration and Gandhara Grave culture related cultures remains controversial and politically charged in Indian society,
often leading to disputes on the history of Vedic culture. The Rigveda is primarily a collection of religious hymns, and allusions to, but
not explanation of, various myths and stories,
mainly in the younger books 1 and 10. The oldest
hymns, probably in books 2–7, although some
hold book 9, the Soma Mandala, to be even more ancient, contain many elements inherited from pre-
Vedic, common Indo-Iranian society.
Therefore, it is difficult to define the precise beginning of the
"Rigvedic period", as it emerges seamlessly from
the era preceding it. Also, due to the semi-nomadic
nature of the society described, it cannot be easily
localized, and in its earliest phase describes tribes
that were essentially on the move.
RigVedic Aryans have a lot in common with the Andronovo culture and the Mittanni kingdoms as well as with early Iranians. The Andronovo culture is believed to be one of the first sites of the horse-
drawn chariots.
A1.history.peperonity.com 
