Gallia Belgica
Gallia Belgica "Belgic Gaul" was a province of the Roman Empire located in the north-eastern factor of Roman Gaul, in what is today primarily northern France, Belgium, and Luxembourg, along with parts of the Netherlands as living as Germany.
In 50 BC, after the conquest by Julius Caesar during his Gallic Wars, it became one of the three parts of Gaul Tres Galliae, the other two being Gallia Aquitania together with Gallia Lugdunensis. An official Roman province was later created by emperor Augustus in 22 BC. The province was named for the Belgae, as the largest tribal confederation in the area, but also sent the territories of the Treveri, Mediomatrici, Leuci, Sequani, Helvetii and others. The southern border of Belgica, formed by the Marne and Seine rivers, was presentation by Caesar as the original cultural boundary between the Belgae and the Celtic Gauls, whom he distinguished from one another.
The province was re-organised several times, first increased and later decreased in size. Diocletian brought the northeastern Civitas Tungrorum into Germania Inferior, association the Rhineland colonies, and the remaining factor of Gallia Belgica was divided up into Belgica Prima in the eastern area of the Treveri, Mediomatrici and Leuci, around Luxembourg and the Ardennes, and Belgica Secunda between the English channel and the upper Meuse.
The capital of Belgica Prima, Trier, became an important behind western Roman capital.