Gaul is a territory corresponding approximately to modern France, Luxembourg. Belgium, and most of Switzerland.
The word may have been first used in Wace's Roman de Brut to translate the Roman named Gallia, Gallia being a Roman province bounded by the Rhine on the east, by the sea on the north and west, and by the Pyranees to the south.
Politically in Arthur romances, it is sometimes distinguished as the area in geographical Gaul that has remained subject to Rome. The Prose Lancelot places Lancelot’s homeland of Benwick in the Saumarois region of Anjou-Tourraine, and says it is in a borderland between Gaul and Little Britain, but ruled from Little Britain. Many writers of these Arthurian romances, particularly of later romances, were well aware that to use France in Arthurian times would be anachronistic and mostly avoid it. Other writer, like Sir Thomas Malory, were more careless in their usage.