From the Wikipedia page 
The Vaucluse (French pronunciation: [vo.klyz] ; Occitan: Vauclusa in classical norm or Vau-Cluso in Mistralian norm) is a department in the southeast of France, named after the famous spring, the Fontaine-de-Vaucluse. The name Vaucluse derives from the Latin Vallis Clausa (closed valley) as the valley here ends in a cliff face from which emanates a spring whose origin is so far in and so deep that it remains to be defined.
Vaucluse was created on 12 August 1793 out of parts of the departments of Bouches-du-Rhône, Drôme, and Basses-Alpes (later renamed Alpes-de-Haute-Provence). The then rural department was, like the nearby city of Lyon, a hotbed of the French Resistance in World War II.