cantons: Geneva, Vaud, Neuchâtel, and Jura; and the co-official language – along with German – in the cantons of Valais, Bern, and Fribourg, French speakers forming the majority of the population in the regions of Lower Valais, Bernese Jura and Fribourg francophone ("French-speaking Fribourg"). Bernese Jura is an administrative division of the Canton of Bern, whereas the two others are informal denominations. Geography The linguistic boundary between French and German is known as (lit. "rösti ditch", adopted in Swiss French as ). The term is humorous in origin and refers both to the geographic division and to perceived cultural differences between the Romandy and the German-speaking Swiss majority. The term can be traced to the WWI period, but it entered mainstream usage in the 1970s in the context of the Jurassic separatism virulent at the time. The linguistic boundary cuts across Switzerland north-to-south, forming the eastern boundary of the canton of Jura and then encompassing the Bernese Jura, where the boundary frays to include a number of bilingual communities, the largest of which is Biel/Bienne. It then follows the border between Neuchâtel and Bern and turns south towards Morat, again traversing an areal of traditional bilinguism including the communities of Morat and Fribourg. It divides the canton of Fribourg into a western French-speaking majority and an eastern German-speaking minority and then follows the eastern boundary of Vaud with the upper Saane/Sarine valley of the Bernese Oberland. Cutting across the High Alps at Les Diablerets, the boundary then separates the French-speaking Lower Valais from the Alemannic-speaking Upper Valais beyond Sierre. It then cuts southwards into the High Alps again, separating the Val d'Anniviers from the Mattertal. Historically, the linguistic boundary in the Swiss Plateau would have more or less followed the Aare during the early medieval period, separating Burgundy (where the Burgundians did not impose their Germanic language on the Gallo-Roman population) from Alemannia; in the High Middle Ages, the boundary gradually shifted westward and now more or less corresponds to the western boundary of the Zähringer possessions, which fell under Bernese rule in the late medieval period, and does not follow any obvious topographical features. The Valais has a separate linguistic history; here, the entire valley, as far as it was settled, would have been Gallo-Roman speaking until its upper parts were settled by Highest Alemannic speakers entering from the Bernese Oberland in the high medieval period (see Walser). Language