The German national anthem Deutschlandlied was written in 1841, giving four water bodies as borders of the en:German language Sprachraum of the time "Von der Maas bis an die Memel, von der Etsch bis an den Belt". This maps outlines them, and the border of the en:German Confederation of the time.
Russian version.
This file was derived from: Maas Memel Etsch Belt (svg).svg:
Maas_Memel_Etsch_Belt_(svg).svg: Mueck Derivative work: Maximilian Dörrbecker (Chumwa) *derivative work: DR