Quercy (kĕrsēˈ) [key], region and former county, SW France, now divided between Lot and Tarn-et-Garonne depts. Cahors is the chief city. It consists of arid limestone plateaus (causses), cut by fertile valleys of the Lot, Dordogne, and Aveyron rivers. Sheep raising is the chief activity in the causses; the famous Rocamadour cheese is made from sheep's milk. Of Gallo-Roman origin, Quercy (also known as Cahorsin) became (9th cent.) a fief of the counts of Toulouse. It was savagely contested during the Hundred Years War, after which it was united (1472) with the French crown and included in Guienne prov.