The areas of western Bohemia and eastern Slovakia belong to different mountain and drainage systems. All but a minute fraction of the Bohemian region drains into the North Sea by way of the Vltava (Moldau) and Labe (Elbe) rivers. The hills and low mountains that encircle this area are part of the north-central European uplands that extend from southern Belgium, through the central German lands, and into Moravia. These uplands, which are distinct from the Alps to the south and the Carpathian Mountains to the east, are known geologically as the Hercynian Massif. Most of Slovakia drains into the Danube (Dunaj) River, and its mountains are part of the Carpathians, which continue eastward and southward into Romania.

The uplands of Moravia are a transition between the Hercynian Massif and the Carpathians and are in contrast with them by having more nearly north-south ridge lines. Most of Moravia drains southward to the Danube, but the Odra (Oder) River rises in the northeast and drains a sizable portion of the northern region