go check all maps before british. Arunachal pradesh was never part of India. Infact, nepal has been under indian empire control from time to time. There is a much stronger case for Nepal to be part of india than arunachal pradesh. It was only under british that the core of NE. india becamee part of india. British did the macmohan line so india and china keep fighting each other. It was a standard british tactic.
