High Quality Content by WIKIPEDIA articles! Pas-de-Calais is a department in northern France. Its name is the French equivalent of the Strait of Dover, which it borders. Inhabited since prehistoric times, the Pas-de-Calais region was populated in turn by the Celtic Belgae, the Romans, the Germanic Franks and the Alemanni. During the fourth and fifth centuries, the Roman practice of coopting Germanic tribes to provide military and defense services along the route from Boulogne to Cologne created a Germanic-Romance linguistic border in the region that persisted until the eighth century.