You will have to read about past conflict (1962) and skirmishes (1967), that have taken place between India and China, to get an idea about the security concerns of these two nations. A lot of vital info has been kept secret by both the nations. I have been trying to study the reasons, policies and military history of both the govts that led to the past war. It is very difficult as most of the Chinese information is not in english, and being an Indian I have no access to a translator to read those documents, and a lot of Indian info is still secret.
However, ask some questions and I will try and do justice to them. Your present question is too general, be a little more specific. BTW I am Indian.