Does the Arunachal Predesh really belongs to India?

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I've seen a post from an Indian friend that states the mass of land belongs to India for a long time.I'm sorry I cant find it now. Is there any Indian friends can make some evidence?As I know,the official claim in China is that more than 90 thousand kilometers of chinese lands are occupied by India.And the Chinese government has been demanding the sovereignty since the end of Indo-Sina war. From china's publications,you can easily find many evidences to prove those lands belong to China since before Qing Dynasty(500 years ago).And from the natives' appearance(as shown in the photo below),its clearly and obviously the East Asians(cause only one photo was allowed,so I just post up the first one).Its more close to Chinese ,not the Indian.Huh? Anyone can deny it?