According to Anton Weiss-Wendt, the field of comparative genocide studies has very "little consensus on defining principles such as definition of genocide, typology, application of a comparative method, and timeframe." According to Professor of Economics Attiat Ott, mass killing has emerged as a "more straightforward" term. Several different terms are used to describe the intentional killing of large numbers of noncombatants. 7.9 People's Democratic Republic of Ethiopia.7.4 Socialist Federal Republic of Yugoslavia.5.2 Great Leap Forward and the Great Chinese Famine.5.1 Campaign to Suppress Counterrevolutionaries.4.2.4 Soviet killings during World War II.4.2.1 Mass deportations of ethnic minorities.The exact nature of the killings remains a politically and scholarly divisive issue. Many memorials exist to commemorate the victims of communism, especially in formerly communist countries. Very few communist leaders have been legally prosecuted for mass killings. In Cambodia, under the rule of the Khmer Rouge and its leader Pol Pot, the Cambodian genocide killed nearly a quarter of the population from 1975–1979. To what extent the famines in either country were attributable to their leaders or to communism is debated. In China, the majority of killings occurred under the rule of Mao Zedong (1949–1976) the total number killed varies by tens of millions depending on whether the Great Leap Forward and the ensuing Great Chinese Famine are counted. In the Soviet Union, the Holodomor famine and Stalinist period (1927–1953) saw the majority of killings. The three largest contributors to the death toll are the Soviet Union, the People's Republic of China, and Democratic Kampuchea (modern day Cambodia), with other states making up a fraction of the death toll. In addition to mass killings, terms that are used to define such killings include democide, politicide, classicide, genocide, crimes against humanity, holocaust, and repression. Estimates account for executions, deaths from man-made and intentional famines, as well as deaths that have occurred during forced labor, deportations, or imprisonment. Death estimates vary widely, depending on the definitions of the deaths that are included in them and the political perspectives of those performing such tallies.
Mass killings under communist regimes occurred throughout the 20th century. Not to be confused with Crimes against humanity under communist regimes.