Sri Lanka has three main ethnic populations (Singhalese, Tamil and Moors) and they generally live harmoniously side by side.
By far the bulk of the population is Singhalese Buddhist. (74% - Wikepedia) Originally derived from a renegade Indian Prince who landed in Sri Lanka with a band of followers over 2,500 years ago. They rapidly built up a sophisticated agrarian economy and culture.
Living in Sri Lanka is a wonderfully enriching experience where we can learn totally different ways of seeing life and the world. We also learn patience ;-)