The lords of the castle became important local magnates, acquiring during the centuries some key and highly lucrative customs rights on the Rhine.

When the latter line expired in 1583, its property went to Hesse-Kassel (or Hesse-Cassel), which added the inherited part of Katzenelnbogen to its side-line principality of Hesse-Rotenburg.

In 1945, Hesse-Darmstadt was united with most of the Prussian province of Hesse-Nassau, which included the former Hesse-Kassel along with Nassau and the formerly Free City of Frankfurt, to form the federal state of Hesse.

Historians have speculated that the name derives from Cattimelibocus, a combination of two words: the ancient Germanic tribal name of the Chatti and Melibokus, a generic Roman name for 'mountains'[clarification needed].

[3][4] The theory is based on the name Μηλίβοκον (Mēlíbokon), used by Ptolemy specifically for a mountain range farther east: the Harz, the Thuringian Forest or both.