This book presents a new theory of ethnic cleansing, based on its worst manifestations - the genocides of the colonial era, the Armenian genocide, the Nazi Holocaust, the genocides in Cambodia, Yugoslavia and Rwanda, as well as on softer examples (Early Modern Europe, modern India and Indonesia). The extermination of peoples is a phenomenon of Modernity - the “dark side of democracy.” It occurs where demos (democracy) is confused with ethnos (ethnic group). The danger arises when two rival ethno-national movements claim to create their own states on the same territory. Escalation is not simply the result of the actions of “evil elites” or “primitive peoples.” It occurs as a result of complex processes of interaction between leaders, activists and groups supporting ethnic nationalism. Understanding these complex processes can help inform policies that prevent future ethnic cleansing. Michael Mann is a professor of sociology at the University of California, Los Angeles, and the author of The Origins of Social Power (4 vols., Cambridge, 1986-2012) and The Fascists ( Cambridge, 2004). In 2006, M. Mann’s book “The Dark Side of Democracy. Explaining Ethnic Cleansing won the American Sociological Association's Barrington Moore Award for the best book in comparative and historical sociology.