As we have seen, concentrating Jews in ghettos was not part of a methodical process to isolate the Jews from their surroundings in Poland, but a parallel development; hence we should give some attention to the meaning of the term “ghettoization.” The research literature refers not only to the establishment of physical ghettos but also to a process that includes the segregation of the Jews from the surrounding society and their concentration in certain locations. Philip Friedman, for example, devoted a section of his important essay, “The Jewish Ghettos of the Nazi Era,” to “‘Ghettoization’ Attempts in Western, Southern, and Central Europe,” immediately after a section on the “Crystallization of the Segregation Policy.” Here he discussed the concentration of Jews in various cities across Europe. But the examples he cited (such as in Slovakia) are not sufficiently representative: they were either concentrations of Jews as a preliminary step to deportation or ghettos in the old, pre-1938 sense. Hilberg, as we have seen, identified ghettoization, as a concept, with one phase of the emerging anti-Jewish policy, that of residential concentration and segregation, which began in the late 1930s. In the wake of these two scholars, the term “ghettoization” came to refer to all processes to isolate the Jews.