The ancient Nagas were a powerful tribe who are often mentioned in accounts of various rulers. They are even mentioned in the Rig Veda, the oldest of the Hindu religious scriptures. Is it possible that they were pushed towards the North-East from the main 'Aryavarta' region?
I am not sure.but those ancient nagas ,later converted to buddhisim,became ruler,buddhisim ruled india for 1200 years.later with the formation of Hindu religion(from vedic) ,the buddhist followers were converted to hindusim.some strong adherents of buddhism became untouchables.e.g.SCs of maharastra ref-who were untouchable.
since Naga is a Mongoloid race,west bengla,orrisa,bihar were strong region of buddhist the North east must be connected.Naga is not a race in pure form ,but it is culture IMHO.