The Nahegau was a county in the Middle Ages, which covered the environs of the Nahe and large parts of present-day Rhenish Hesse, after a successful expansion of the narrow territory, which did not reach the Rhine, to the disadvantage of the Wormsgau. Among other expansions were Ingelheim in 937, Spiesheim in 960, Saulheim in 973 and Flonheim in 996, until after the end of the expansion the Selz set the southern limit and the limit to the Wormsgau.
The Nahegau was among the central possessions of the Salian dynasty, to which from the mid-11th century the Emichones succeeded. The family of the Emichones divided itself later into the Counts of Veldenz, the Wildgraves and the Raugraves. Perhaps the Leiningen family descended from the Emichones as well.
Counts in Nahegau were: