The Germans had no respect for such things, and offered no mercy to conquered peoples. A Celtic peasant might not experience much of a drop in his living standard if he were ruled by Germans. The various tribes leaving the Rhineland had few places to go. They could not have taken Belgic land, and many other Celtic tribes were too powerful for them to fight. They finally settled in Armorica, a place slow to change, where customs and beliefs of the megalithic age lingered on.
Information is sparse.
Perhaps the new arrivals had connections with Celtic people already there, or perhaps the indigenous people felt that these Celts might form a buffer between them and the Belgae. All we can be sure of is that, by the time of Caesar, several Celtic tribes occupied Armorica. Although each tribe was independent, they were united by a similarity in their artistic styles that hearkened back to the styles of the Rhineland. The Roman invaders forced cooperation on the Armoricans. When Crassus came with a single legion, each stronghold tried to defend itself individually, with little regard for the country as a whole.