 This town and Vasio (Vaison-la-Romaine) were not on the mountains.They were at the foot of the first prealpine ridges, at the edge of the plain of the Rhône (the Dentelles de Montmirail were just to the south of Vasio; the Éssaillon, Garde-Grosse, Saint Jaumes and Vaux formed a half crescent by Noviomagus).During the 4th century BCE, the Celtic Vocontii became settled there, with an oppidum south of modern Vaison (Garcia p. 168); this seems to have been used to control trade between the Rhône and Durance rivers (Meffre).