The prevalence of French has been shown to be due to the direction of travel in this mountainous region. The two St. Bernard Passes, the “Col du Grand St. Bernard” and the “Col du Petit St. Bernard,” have determined the route along which human displacements could be undertaken with a minimum of effort.[43] The road encircles that famous Alpine peak. It has acted as a channel through which French has flowed into areas of Italian and German speech. This instance may well be adopted as a classical example of the influence of geography in the distribution of linguistic areas. The origin of linguistic differences in Switzerland may be traced to the dawn of the period that followed Roman conquest. At the time of Caesar’s invasion of Helvetia, the mountainous land was peopled by men of Celtic speech. Barbarian invasions put an end to the uniformity of language prevailing in the country. Romance language survived in the highlands of the Jura and throughout the western sections of Switzerland. The Celtic and Latin languages spoken in the first five centuries of our era gave birth to French. The Burgundian conquerors themselves adopted this language at the time of the foundation of the first kingdom of Burgundy. German, on the other hand, is a relic of Teutonic invasion of eastern and central Switzerland. In the sixth century, the Alemanni took advantage of the weakening of the Burgundian Kingdom to spread beyond the Aar and overrun the attractive lake district. By the eleventh century they had succeeded in imposing their language on the native populations of the Fribourg and Valais country. The reunion of the two states under the reign of Clovis failed to unify the language of Switzerland. A split occurred again after the partition of Charlemagne’s dominions, followed by another period of joint political life until the death of Berthold V of Zähringen. After this event the consolidation of languages became impossible in Switzerland. The rivalry of the Alemanni and Burgundian kingdoms was maintained among Swiss populations. In feudal days, German Switzerland acknowledged the suzerainty of Hapsburg counts. Romanic Switzerland, on the other hand, leaned towards the House of Savoy.