Nazi propaganda poster of the Third Reich in 1939 (dark grey) after the conquest of Poland. It depicts pockets of German colonists resettling into Polish areas annexed by Nazi Germany from Soviet controlled territories during the "Heim ins Reich" action. The outline of Poland (here superimposed in red) was missing from the original poster. Source: https://en.wikipedia.org/wiki/Generalplan_Ost

"The further east the Jewish communities were located the shorter was their path to the place of annihilation. Within the Soviet Union where the Jewish communities were hardly organized effectively within a ghetto, the Jewish population was usually summoned by the SS men and executed near the town where they were concentrated. In Poland where the ghettos and Jewish self-government had existed for several years, the Germans took precautions not to annoy the Jews by the executions in the vicinity of the towns but disposed of them in secret and distant extermination camps. In this way the Germans could secure initially the cooperation of the Jewish Councils which readily supplied the requested quotas "for resettlement and work in the East" from the overpopulated, starved, and disease-ridden ghettos.

The Nazis went to greater pains to preserve the appearance of "enlistment for work" in other countries under their occupation and especially in their satellites. In some cases there were regular contracts offered to the semi-independent governments which provided for the delivery of Jews for the "work in the German East" and these even included a clause for eventual return if the governments concerned wanted them back. The "enlisted" Jews were then transported eastward, sometimes as far as Riga and Minsk, but usually to the closer extermination camps in Poland. Sometimes to show off Germany as a "cultured nation," the Nazis transported the Western Jews in luxurious pullman trains and supplied them with fancy camping equipment (like tents and field-kitchens) which, of course, were taken away at the place of destination."

Kamenetsky, Ihor (1961): Secret Nazi Plans for Eastern Europe. New York: Bookman Associates. 168–169.