The regular transfer of ethnic nationals among nations, authorized according to the Potsdam Conference, proceeded from 25 January 1946 until October 1946. An estimated 1.6 million "ethnic Germans" (most of them also had Czech ancestors; and even Czechs, who spoke mainly German over the last years), were deported from Czechoslovakia to the American zone of what would become West Germany. An estimated 800,000 were deported to the Soviet zone (in what would become East Germany). Estimates of casualties related to this expulsion range between 20,000 and 200,000 people, depending on source. Casualties included primarily violent deaths and suicides, rapes, deaths in internment camps and natural causes.