[2] In 57 BC, Julius Caesar led the conquest of northern Gaul, and already specified that the part to the north of the Seine and Marne rivers was inhabited by a people or alliance known as the Belgae.

These were the leaders of the initial military alliance he confronted, and they were also more economically advanced (and therefore less "Germanic" according to Caesar's way of seeing things) than many of their more northerly allies such as the Nervii and Germani Cisrhenani.

[6] Due to the Belgic coalition's size and reputation for uncommon bravery, Caesar avoided meeting the combined forces of the tribes in battle.

Agrippa made the divisions on what he perceived to be distinctions in language, race and community – Gallia Belgica was meant to be a mix of Celtic and Germanic peoples.

Modern historians however view the term 'Gaul' and its subdivisions as a "product of faulty ethnography" and see the split of Gallia Comata into three provinces as an attempt to construct a more efficient government, as opposed to a cultural division.

Additionally, local notables from Gallia Belgica were required to participate in a festival in Lugdunum (modern Lyon), which typically celebrated or worshipped the emperor's genius.

Emperor Domitian reorganized the provinces in order to separate the militarized zones of the Rhine from the civilian populations of the region.

The newer Gallia Belgica included the cities of Camaracum (Cambrai), Nemetacum (Arras), Samarobriva (Amiens), Durocortorum (Reims), Dividorum (Metz) and Augusta Treverorum (Trier).

In 173, the later emperor Didius Julianus, then governor of Gallia Belgica, had to repel a serious invasion of the Chauci, a Germanic tribe that lived along the shores of the Wadden Sea at the respective northern and northwestern coast of present-day Netherlands and Germany.

Further the capitals in the areas of the former tribes of the Atrebates, Morini and the Nervians were either burnt down (Nemetacum (Arras)) or had to be rebuilt in the last quarter of the second century, Colonia Morinorum (Thérouanne) and Bagacum Nerviorum (Bavay).

With the Gallic army defeated and not returning to the Rhine border, the Franks overran the neighbouring province of Germania Inferior.

The Rhineland (to the Ripuarian Franks) and the area between the Rhine and the main road between Boulogne and Cologne, present-day South Holland, Zeeland, Flanders, Brabant and Limburg, the last three in both the present-day Netherlands and Belgium (to the Salian Franks) were de facto lost forever for the Roman empire.

This gave the Salian Franks a base from which they could expand some 130 years later, beginning after the disastrous Rhine crossing in 406, to conquer the whole area of the former province of Gallia Belgica and start the Merovingian kingdom.

The eastern part of Gallia Belgica, especially the valley of the Moselle became very prosperous in the fourth century, particularly in the decades that Augusta Treverorum (Trier) was the capital of the Western Roman Empire.

They subsequently destroyed large parts of Gallia Belgica, before eventually moving on to Hispania (present-day Spain).

This invasion and the accompanying widespread destruction broke the backbone of Roman power in at least the northern part of Gallia Belgica.

After this invasion the Franks were able to conquer valuable agricultural land south of the Via Belgica, the very important main road between Cologne and Boulogne, that had been the backbone of Roman defense strategy between 260 and 406.