It is well known that ‘nation’ or nation-states are the most important organizing principles of governance, which are adopted by many states across the globe. Soon after the end of the Second World War, all the post-colonial countries followed the European model of the nation-state as a modern way of governance, which promotes cultural and political uniformity. In this context, the article has examined the effectiveness of the European nation-state model, which is adopted in post-colonial South Asian states, and in this regard, it has taken the case study of Chittagong Hill Tracts of Bangladesh. The study shows that, even if Bangladesh is one of the least heterogeneous states among all South Asian countries, it is still grappling with the crisis of ethnic conflicts and violation of minority rights, and insurgency in the state. As a result, it has not only brought tensions within Bangladesh but also, it is causing security concerns too in the neighboring state of India by pushing the migration of ethnic minorities and population-made victims out of it. Like other South Asian countries, Bangladesh is also facing the crisis of ethnonationalism, which is undermining the ethos of multiculturalism and the process of nation-state building.