The territory extended within the triangular area outlined by the River Garonne, the Pyrenees and the Bay of Biscay, as described by Julius Caesar in his Commentarii de Bello Gallico for Gallia Aquitania.

It seems clear that at the time of the lower empire (2nd to 4th century),[2] the nine peoples were granted by the emperor the right to detach from the Gauls proper (Celts) by means of the magister pagi Verus and, as a result, a celebrating altar was erected which was dedicated to the deity of the pagus.

These civitas are in turn identifiable with present-day towns and cities as follows: Auch, Dax, Lectoure, Comminges, Couserans, Buch and Born, Béarn or Lescar, Aire-sur-l'Adour, Bazas, Tarbes, Oloron, Eauze.

These recordings feature names of deities, persons and places with easily identifiable similarities to present-day Basque, a fact that provides, along with current and ancient place-names north of the Pyrenees (e.g. Illiberris mentioned by Ptolemy on the eastern fringes of Novempopulania)[5] and traces of Basque in the Gascon language (especially in the Béarnese dialect), the basis for an Aquitanian proto-Basque theory.

Accounts of events taking place at that time on the territory of Novempopulania are confusing and blurred, and so are the names of the peoples and their geographical locations, who are as of now dubbed Vascones, Wasconia, Guasconia (as opposed to the Spanoguasconia, according to the Ravenna Cosmography) with no clear boundaries.

Novempopulania was to become the core region of the Duchy of Vasconia, which was established by the Franks at the beginning of the 7th century with a view to holding back the Basques, but which often conducted a semi-autonomous governance of Basque-Aquitanian background.