The Segovellauni dwelled in the valley of the Rhône river, south of the Isère river and west of the Vercors Massif, around the present-day city of Valence. This land, corresponding to the modern Valentinois region, was called the 'Island' by Polybius and Livy in their description of Hannibal's crossing of the Alps in 218 BC, for it was situated between the Rhône and the Isère, near the confluence of the two rivers. In the south, their territory stretched down to the Drôme river, or perhaps further south into the plain of Montélimar. It likely covered the Vivarais region west of the Rhône, between the Eyrieux and rivers.