The Qianlong Emperor then ordered the genocide of the Dzungars, moving the remaining Dzungar people to the mainland and ordering the generals to kill all the men in Barkol or Suzhou, and divided their wives and children to Qing forces, which were made out of Manchu Bannermen and Khalkha Mongols. Qing scholar Wei Yuan estimated the total population of Dzungars before the fall at 600,000 people, or 200,000 households. Oirat officer Saaral betrayed and battled against the Oirats. In a widely cited account of the war, Wei Yuan wrote that about 40% of the Dzungar households were killed by smallpox, 20% fled to Russia or Kazakh tribes, and 30% were killed by the Qing army of Manchu Bannermen and Khalkha Mongols, leaving no yurts in an area of several thousands li except those of the surrendered. During this war Kazakhs attacked dispersed Oirats and Altays. Based on this account, Wen-Djang Chu wrote that 80% of the 600,000 or more Dzungars (especially Choros, Olot, Khoid, Baatud and Zakhchin) were destroyed by disease and attack which Michael Clarke described as "the complete destruction of not only the Dzungar state but of the Dzungars as a people." Historian Peter Perdue attributed the decimation of the Dzungars to an explicit policy of extermination launched by the Qianlong Emperor, but he also observed signs of a more lenient policy after mid-1757. Mark Levene, a historian whose recent research interests focus on genocide, has stated that the extermination of the Dzungars was "arguably the eighteenth century genocide par excellence." The Dzungar genocide was completed by a combination of a smallpox epidemic and the direct slaughter of Dzungars by Qing forces made out of Manchu Bannermen and (Khalkha) Mongols.