[vladimir998]

Hasn’t this been known since the 19th century? The Gauls were much more sophisticated than other barbarians in Europe at the time. They had a thriving agriculture, could field massive armies, kept up good communications under the Roman assault, had large towns with sophisticated wooden defensive systems (sadly for the Gauls, they had few stone defensive structures), etc.

[Lucius Cornelius Sulla]

It took Julius Caesar with up to 10 legions (72,00 men, counting auxiliaries and cavalry), and often with most of the Gallic tribes as allies nearly 10 years to conquer Gaul. Naturally this means that they were pushovers!