[1] In ancient Gaul the region was the country of the Nitiobroges with Aginnum for their capital, which in the fourth century was the Civitas Agennensium, which was a part of Aquitania Secunda[2] and which formed the diocese of Agen.

[3] Having in general shared the fortunes of Aquitaine during the Merovingian and Carolingian periods, Agenais from about 886 became an hereditary county in the part of the country now called Gascony (Vasconia).

The marriage of Eleanor of Aquitaine with the future Henry II of England in 1152 brought the county under the sway of the Plantagenet house of Anjou.

[4] In 1561, Guyenne was made a province, and included Bordelais, Bazadais, Limousin, Périgord, Quercy, Rouergue, Agenais, Saintonge, and Angoumois.

At the end of the Ancien Régime it formed part of the Gouvernement of Guienne, and at the Revolution it was incorporated within the département of Lot-et-Garonne, of which it constitutes nearly the whole.