"The Aryan influence became so widespread and penetrating that even minor Vedic customs and rituals deep rooted in the life of the common people... Aryanisation led to a unification of the innumerable tribal groups particularly in the Brahmaputra valley primarily through the development of a language which was a direct descendant of Magadhi Apabhramsa’."
January 1, 1970
https://en.wikiquote.org/wiki/History_of_Assam