This article discusses political genocide in postcolonial Asia, looking at Indonesia, Cambodia, and China. Mass political killing presents a special problem in genocide studies. The slaughter of human beings because of the political beliefs and attitudes they held, or were presumed to have held, cost millions of lives during the twentieth century. The Indonesian killings of 1965–6 cost half a million lives and the killings during the Cultural Revolution in China claimed a million lives. Although these are massive death tolls, both episodes involved only a relatively small proportion of the total population of those two countries. The Cambodian killings, by contrast, claimed twenty-five per cent of a population of eight million in little more than three years. These three political genocides took place within little more than a decade. They occurred in the context of the Cold War, a time of acute polarization between secular ideologies that is unprecedented in world history.