International audienceAbstract: Some geographical names are frequently attested with two different prepositions, contrary to what classical grammars suggest. This article studies this phenomenon before names of ancient regions, relying on specialized corpora, in order to determine to what extent chronological, typological, or geographical factors are involved in the selection of preposition before names of old regions. The use of Guillaumian theory helps to explain the observed usages, and serves as a support to suggest a link with the evolution of socio-cultural representations since the 1950s.Lorsque des noms de régions anciennes (ou terroirs) sont attestés avec plusieurs prépositions, pour une expressiontraditionnellement considérée comm...