If China can lay claim to sovereignty to the almost entire SCS citing history then India can equally lay claim to these regions including China itself where they had exported Budhism.In fact ancient India had businesss and cultural ties in the entire SEasia starting with China right up to java ,Sumatra,Indonesia..japan.However in modern civilized times it is the latest International law which have to be honored to maintain the semblance of order.
The Chinese need a lesson just like the Japanese had.... Some never learn..even at a great human cost.. It means nothing to them... just the single minded purpose of domination,, and somehow believing that it is all that matters.
There is no need for India to overtly engage/ contain China now but can encourage all the Chinese neighbours to do so. Vietnam, Japan, Philippines, Taiwan & South Korea are all frustrated with Chinese Bullying its just a matter of time China might start a fight which will eventually end up as sanctions against its global trade and its global ambitions. India just have to facilitate the Chinese neighbours to go against China especially against the South China Sea artificial island buildup.
There is nothing new to Indian about Chinese. They will do what they have decided to do. This dragon country slowly but steadily expanding its power. Now they have entered in Indian Oceans. Its a wake up time for India... now or never. China is never trustworthy country.