I doubt that you know the history of the area at all, judging by your remarks. India is a multi-cultural state; so, in some respects, is China, but she tends to force everyone into the same template.
Most of the tribes on the southern slopes of the Himalayas followed Tibetan Buddhism, which was very largely nourished by Indian teachers and reformers from the 13th century onwards. It was the intervention of the Himalayas that protected Tibetan Buddhism in Tibet from being swept away by the events of that period, which did in fact sweep away the equivalent Indian Buddhism, identical in every respect.
None of the tribes are related to ethnicities in China; they are related to Tibeto-Burmese stock, which is quite distinct from Chinese stock. A little study would help you immeasurably in this regard. There was not even any direct relationship with China; it is known that trade took place in a series of exchanges along the north-south axis, where each tribe took goods at either the northern or the southern frontier, and handed them over at the other. So Indian goods flowed from the valley of the Brahmaputra to Tibet, to the valley of the Brahmaputra as it flowed through Tibet, and Tibetan goods came back in turn through the same channels. There was no incursion of Tibetans into AP, except the corner of the Tawang Monastery and its lands.
Of the states of the north-east that had independence movements against the British, it was only Nagaland that had anything like a viable movement. There was nothing in AP to match it.
There was no British presence in AP. That presence was first instituted in the 50s by Indian civil servants and the question of taking over a British legacy did not arise.
Learn your history.
