Buddhist nationalism has contributed to expanding religious violence in many South Asian countries. The roots of this violent form of nationalism are complex and multi-faceted, making a clear solution difficult to achieve. Thailand, Sri Lanka, and Burma are some of the most pressing and violent case studies in South Asia today and can illustrate the reliance of Buddhist nationalists on ethnoreligious identities to relegate non-Buddhists to second-class status, to the point of massive acts of violence and aggression. This paper seeks to illuminate the complex social history driving the rise of Buddhist nationalism in these countries, particularly strong military-religion relationships, histories of colonial oppression, long-standing cultural tensions, and Western rhetoric regarding Buddhist values. In the modern period, Buddhism has become increasingly politicized for the benefit of nationalist movements. Buddhist extremism is largely derived from the political contexts of increased ethnic nationalism and the influence of monks in Buddhist communities. Buddhist extremism often has more to do with ethnic tensions than religious tensions, though religious motivations are still substantial in many of the conflicts involving Buddhist extremists. In South Asian countries, the most substantial Buddhist nationalist movements tend to practice Theravada Buddhism. This Buddhist practice differs from other forms of Buddhism on the topic of non-violence and peace, aligning more closely with nationalist values and the connections between religion and state power; some Theravada sects view non-Buddhists as subhuman or second-class.