The Eastern Frontier

According to Caesar, the boundary between the Biturige and the Aeduan was the natural frontier constituted by the Loire.

But in reality, the Aeduan territory encroached onto the left bank of the river since we know that, in 58 BC, Caesar authorised the Aeduans to allow the Boïens tribe to settle within their lands and that the Boïens built their main oppidum in a place called Gortona or Gorgobina.

The Southern & Western Frontiers

The southern and western frontiers correspond to the borders of the diocese of Clermont-Ferrand, following the current boundary between the departments of the Allier and the Puy-de-Dôme. Aigurande stands on the site of the ancient Equoranda, a border town separating the Biturige and the Lemovice. Continuing west, the Biturige frontier follows fairly closely that of the Indre, including the Brenne. Ingrandes (Fines) marked the border with the Pictones. To the north, the boundary between the Biturige and the Turons coincides exactly with that between the departments of the Indre and Indre-et-Loire.

The line of the frontier between the Biturige and the Turons is confirmed during the Late Empire in a note by Sulpice-Sévère stating that Clion-sur-Indre (Claudiomagus), situated currently about twelve kilometers from the border between the Indre and the Indre-et-Loire departments, was the location of the boundary between the two tribes.

The Northern Frontier

This border poses something of a problem. Going back to De Bello Gallico; after having burnt Cenabum (Orléans), Caesar made his way towards Bourges "crossing the Loire and arriving in the lands of the Biturige". Thus, the frontier between the Carnutes and the Biturige was situated some distance south of the Loire. On his way he laid siege to Noviodunum, a town which he explicitly states to be Biturige.

Two locations have been postulated for this site: Neung-sur-Beuvron in the Loir-et-Cher and Neuvy sur Barangeon in the Cher. The first is situated 45kms south-south-west of Orléans and the second around 70kms east-north-east. It is possible that a slight later modification was made to the border or that quite simply Caesar made a geographical mistake.