By the time of Caesar's conquests, the Gauls had been in contact with the Romans for a very long time. The reason why they were considered softer than the Germanic tribes is because they traded with the Romans and had access to Roman goods. The Germanic tribes did not have centuries long, direct trade links with Rome and were thus seen as tougher and more rugged and did not have the luxuries of "civilized" living.

The Gauls had made incursions into Italy before.

There were also Gauls in Italy for a very, very long time.