As Chablais ( from the Latin caput lacus " head of the [ Geneva ] lake "), the area is known south of Lake Geneva. The larger western part - the lakeshore around the towns of Thonon -les- Bains and Evian- les- Bains and the catchment area of the river Dranse - part of the French department of Haute- Savoie. The through by the Swiss Rhône share is made up of the Valais district of Monthey and Aigle Vaud district.
The region was among the possessions of the Abbey of Saint -Maurice in 1032 and went on to the House of Savoy. In the Burgundian Wars of the Bernese conquered first in 1475, the area east of the Rhone ( bailiwick Aigle ) and 1536 - together with the Welsh, - the remainder of Chablais. With the Treaty of Lausanne ( 1564) and Thonon ( 1569 ) received the Savoy back most of the territory, only the Bailiwick of Monthey remained the Welshmen. After the Reformation was first introduced in the Bernese part, he was re-Catholicised 1594-1598 by the preaching of the then Bishop of Annecy, of St. Francis de Sales, and the Capuchins.
During the Napoleonic Wars from 1792 to 1815 the Western Chablais belonged as part of Savoy to France. With the return of the now formed from the Duchy of Savoy Kingdom of Piedmont-Sardinia was declared a demilitarized zone. As Savoy 1860 finally came to France, which Chablais, which was also claimed in the years 1859/60 from Switzerland received (→ Savoyerhandel ), also the pre-existing 1919 status of a free zone ( grande zone franchement ), the 3790 km ² (86% of the department of Haute- Savoie) included.