In this paper, based on several types of documents (legal texts, diplomatic correspondence, literary writings, educational works), I examine how factors external to the language, of various kinds, acting in a complex synergy, had an impact on the geographical development and functional diffusion of the idioms present in the ancient States of Savoy at a time when the vernacular languages were asserting themselves and consolidating.
In particular, I focus on the ‘French’ side of the Duchy to show that in these territories the predominance of French in most communicative contexts and the confinement of Franco-Provençal to the sphere of family life and everyday activities depend on political decisions but also on the geographical context and the social and economic fabric: French is the prerogative of the highest classes, who use it carefully and rigorously, distancing themselves not only from Latin tradition but also from regional or dialectal popular culture, while Franco-Provençal remains the prerogative of the most isolated communities and those with more difficulty in accessing education. This divide is visible, on a literary level, by two distinct parallel traditions.