Valle Caudina is in the center of Campania: it is surrounded from the south by Partenio and from the north by Taburnus massif.

The main west entrance is the Stretta di Arpaia, where the Battle of the Caudine Forks may have been fought, between the mountains of Tairano and Castello; another[clarification needed] is the Moiano's gorge.

Instead[clarification needed], the east entrance is the passo of Sferracavallo in the comune of Montesarchio.

Originally, in the valley there was a lake fed by the waters coming from the Taburnus and the Partenio.

Ceramic remnants at San Martino Valle Caudina suggest early settlements dating back to the Bronze Age (1800–1000 BC).