This paper is part of a project titled “A History of Ethnic Conflict in Sri Lanka: Recollection, Reinterpretation and Reconciliation.” The central problem this essay addresses is: how and why historically mixed, often hybrid and multicultural communities transformed into mono-ethnic constituencies, enclaves, and perhaps modern nation states based on ethnic partitions. The paper also traces how new forms of collective identity were invented in the colonial period when the British Raj mapped and classified native populations according to colonial racial science. It also traces how in the post-colonial armed conflict between the Sri Lankan government and the Liberation Tigers of Tamil Eelam fighting for a separate state modern ethnic identities have been consolidated in previously hybrid ‘border areas’. These articles are expected to reach many people, including scholars, media personnel, political activists and NGO personnel, provoking thought and discussion on a range of relevant subjects. Thereby, guiding decision makers at all levels when they aim to establish a viable framework for peace.