This had been discussed numerous times here about the ownership of Arunachal/South Tibet.
On what basis u claim Arunachal,because Ming or Quing dynasty ruled it some light years ago,on this basis we can claim the entire South Asia or the mongols can claim entire Asia,thats ridiculous.
A post of Joe quoted by Cardshape explain's the demographies of Tibet,the culture associated with people,it even do not have stark resemblance with people from Tibet.
If the evidence is all about some pre historic conquest and controlls,it will then always remain disputed.
Qing is not light years ago. Qing was overturned in 1911. After Qing, Beiyang Republic took over the central government, then KMT Republic of China, and then Communist PRC. So throughout the history, China central government has never given up Tibet and even during its weakest time, our officials and their office was still in Tibet, just not the Army.
For example, when the notorious McMahon Line, which India bases it claim on, was drawn, the central government of China refused to recognized it at all even though we have no strength then to driven away the British. Our claim of Tibet is undisputed in the world, including India as well. The supposed "Human Right" is not in this discussion.
So China claim over Tibet is continuous up to today. If South Tibet (AP) was always under control of Tibet, and if China claims Tibet, how could it will not claim South Tibet?
For evidence? I bet every Dalai Lama has its officials there to collect tax and Budala palace should have all the past collection records. After all, Dalai Lama is the supreme leader then to control religion and wealth on every corner of Tibet. I doubt Dalai Lama would NOT even control its birth place. When don't we send historians of both sides there digging those historical journals???
On the contrary, India's presence, besides British, only started after India's independence and Nehru thought it would be good to "go east", which meant grabbing (stealing) more land from neighboring Tibet, which is claimed by China while China was too busy to fight a civil war.
If you want to talk culture association, then a lot of areas in India has no such clear association with your Hindu culture as well. Even in China, Tibet is different from main Han Chinese, the Hmong minority in the South, Mongolian minority in the North and etc all have distinct culture from the main Han Chinese. Even in Russia, those Tajiks, Uzbeks and etc are all different in culture from Russia.
If simply by culture association, the whole world will divided into thousands of pieces.
Historical control is still the most sought evidence in all territorial dispute. Culture association will come secondary if it is really needed.