Most of the lists of forced laborers that are kept in the Arolsen Archives today were compiled as part of the foreigner tracing campaign (Ausländersuchaktion). At the turn of the year 1945/1946, the Allies ordered German local authorities, employment offices, insurance companies, district administrators, hospitals, and other authorities in all four occupation zones to complete various forms and compile lists. The purpose of this was to collect information in order to provide a more comprehensive and more detailed account of non-Germans who were registered in the German Reich before, during, or after the war.
These lists were compiled differently in each occupation zone. In the US zone, index cards and forms were used, and these were marked either with a number or a letter. Each local authority had to fill in special forms for foreigners who died during the war, for instance. Other forms were used for marriages or births of non-Germans. In the British zone, the procedure was less structured and no forms were used, which is why the lists were compiled in very different ways. Information was also collected in the Soviet and French occupation zones. However, due to the increasing tensions between East and West, only a few documents from the Soviet occupation zone initially found their way to Arolsen. This was made up for in part after 1989 when copies were acquired.