According to the Roman ethnography and Julius Caesar in his narrative Commentaries on the Gallic War, Gaul was divided into three main regions: Belgica, Aquitania and Celtica. The inhabitants of Belgica were called Belgae, those of Aquitania were called Aquitani. The inhabitants of the Celtica region called themselves Celts in their own language, and were later called Galli by Julius Caesar:
|“||All Gaul is divided into three parts, one of which the Belgae inhabit, the Aquitani another, those who in their own language are called Celts, in ours Galli, the third.||”|
|“||The whole of Gaul that is comprehended under the one general name of Comata, is divided into three groups of people, which are more especially kept distinct from each other by the following rivers. From the Scaldis to the Sequana it is Belgica; from the Sequana to the Garumna it is Celtica or Lugdunensis; and from the Garumna to the promontory of the Pyrenæan range it is Aquitanica, formerly called Aremorica.||”|
- Caesar, Julius. "Commentarii de bello Gallico".
Gallia est omnis divisa in partes tres, quarum unam incolunt Belgae, aliam Aquitani, tertiam qui ipsorum lingua Celtae, nostra Galli appellantur.
- Pliny the Elder. "Naturalis Historia (4.17 / 4.31)".
Gallia omnis Comata uno nomine appellata in tria populorum genera dividitur, amnibus maxime distincta. a Scalde ad Sequanam Belgica, ab eo ad Garunnam Celtica eademque Lugdunensis, inde ad Pyrenaei montis excursum Aquitanica, Aremorica antea dicta. Universam oram.