During the 1930s, categorisation of so-called enemies of the people shifted from the usual Marxist–Leninist, class-based terms, such as "kulak", to ethnic-based ones. The partial removal of potentially trouble-making ethnic groups was a technique used consistently by Joseph Stalin during his government; between 1935 and 1938 alone, at least ten different nationalities were deported. Germany's invasion of the Soviet Union led to a massive escalation in Soviet ethnic cleansing.