it appears srilanka has always a southindian domination in its 2500 year political history. early cholas, pallavas, latercholas, pandyas, vijaynagar ,nayaks and european rule too. why it was segmented to be a separate nation? it could well have been part of a larger india. if arunachal pradesh or ladakh can be buddist and still be india why not srilanka? even if we take island in its own hypothesis , there are islands like maldives, andamans which are india. the europeans have made a mess. south asia has been divided into eight nations! it should have bee just one or two( if we take a muslim nation idea).
That's pretty much their long term idea. Europeans, where ever they ruled, divided and ruled and when they left, they left with long lasting ethnic issues, so that those nations can never live in peace. This is evident from all the nations history, that Europeans ruled. Exception is USA, because, they stayed their and cleansed the ethnic populace.