In De Bello Gallico describing his conquest of Gaul (58–50 BC), Julius Caesar distinguished between provincia nostra in the south of Gaul, which already was a Roman province in his time, and the three other parts of Gaul: the territories of the Aquitani, of the Belgae, and of the Galli also known as the Celtae. The territory of the Galli extended from the rivers Seine and Marne in the north-east, which formed the boundary with Gallia Belgica, to the river Garonne in the south-west, which formed the border with Gallia Aquitania. Under Augustus, Gallia Lugdunensis was created by reducing in size the territory of the Galli: The portion between the river Loire and the Garonne was given to Gallia Aquitania, and central-eastern portions were given to the new province of Germania Superior. The map shows the extent after these reductions. The date of the creation of Gallia Lugdunensis is under discussion, whether between 27 and 25 BC or between 16 and 13 BC, during Augustus' visits to Gaul.
It was an imperial province, deemed important enough to be governed by an imperial legate. After Diocletian's Tetrarchy (AD 296), it was the major province of a diocese confusingly called Galliae ('the Gaul provinces'), to which further only the Helvetic, Belgian (both also Celtic) and German provinces belonged; with the dioceses of Viennensis (the southern provinces of Gaul), Britanniae (also Celtic) and Hispaniae (the whole Celtiberian peninsula) this formed the praetorian prefecture also called Galliae, subordinate to the western emperor.