Posen-West Prussia
In 1938 the districts of Arnswalde and were disentangled from the Frankfurt Region and merged into the new government region called Frontier of Posen-West Prussia, which was incorporated into the Province of Pomerania. At the same time the districts of Meseritz and Schwerin (Warthe), were transferred out of what had previously been defined as the Province of Posen-West Prussia, now becoming part of the Frankfurt Region.