Nearly two years before the invasion of the Second Polish Republic, between 1937 and 1939, the Sonderfahndungsbuch Polen was being secretly prepared in Germany.[2] It was compiled by the "Zentralstelle IIP Polen" (Central Unit IIP-Poland) unit of the Geheime Staatspolizei or Gestapo ("Secret State Police") with help from some members of the German minority living in pre-war Poland.[3]