The immediate post-Roman period marked the beginning of the language divide in Switzerland as Germanic peoples moved in at different times and in different strengths.

The Alamans moved into northern Switzerland in such large numbers that their language, the ancestor of Swiss German, drove out the local tongue.

The Burgundians, on the other hand, took over the language of the local Gallo-Roman population whom they ruled after settling in Savoy in the west. By this time the original Celtic dialect had given way to a form of Latin, which developed into the various patois of western Switzerland before being taken over by what is now standard French.

Other regions - Rhaetia, which the Alamans failed to conquer, and Ticino under the Germanic Langobards (or Lombards) - also kept their Latin-related dialects, which developed into languages still spoken in those areas today: Rumantsch and Italian.