Two things bring peoples into conflict: the presence of shared resources and the absence of shared culture. In Sri Lanka, the Sinhalese and Tamils do not have a resource sharing issue (as do India and Pakistan over Kashmir). Ours is a problem of two cultures clashing.
When I say culture, I mean both customs and beliefs. Beliefs include both political and personal (e.g. religious). Politically, both Sinhalese and Tamils believe in the same thing — democracy. Both prefer a similar mix of capitalism and socialism. Hinduism and Buddhism are largely compatible and have much in common. In fact, a certain percentage of Buddhists make up for the absence of gods in Buddhism by praying to Hindu gods. Despite attempts by a certain group of Buddhist “extremists” to create problems, Sri Lankan Christians and Buddhists get along admirably. So we may safely rule out beliefs as the main cause of conflict.
Which leaves the remainder of what makes a “culture”, i.e. what makes each group see the other group as a distinct and different group. It cannot be skin color or physiological differences — Sinhalese and Tamils are largely identical. Tamils tend to be slightly darker than Sinhalese, but there are many Sinhalese who are much darker than the average Tamil and are not in anyway treated differently for it. Ours is not a skin color problem.
So if it’s not politics (as in the case of USA vs. USSR), if it’s not religion (as in the case of Indian Hindu’s and Muslims), if it’s not color (as in the case of black Americans), what is it that we use to distinguish ourselves as Sinhalese or Tamils?
This leaves customs, of which language is the most prominent in our case. In fact the names “Sinhalese” and “Tamil” are more often used to mean the respective languages than the groups that speak them. The language difference allows us to view ourselves as two distinct peoples. Other customs such as dress and traditions do play a part in this, but without language they become more like caste or class differences — it may lead to prejudice but rarely to civil war.
I believe that it’s language that has allowed the Sinhalese and Tamils to maintain their original identities throughout the generations. The Sinhalese and Tamils came to Sri Lanka from different places and during different time periods, as did the various European immigrants that eventually became Americans. Americans were able to lose their original national identities in a matter of several generations because of a common language. The Sinhalese and Tamils have remembered their differences for over a thousand years. By the very process of teaching a child to speak Sinhalese, we teach him that he is not a Tamil, and vice versa.