In the Roman era, the region was called “civitas vallensium”, and was under the authority of the Emperor Claudius who had a road constructed from Milan to Mayence, which passed through the Grand-St-Bernard, Martigny, Saint-Maurice, Massongex, StTriphon, Aigle, Yvorne and along the lake. In the 5th century the Burgundians, who came from France, settled between Lyon and Martigny and intermingled with a Gallo-Roman population that had already been decimated by invasions. A Burgundian king, Saint-Sigismond, founded the Abbey of St-Maurice in 515 and granted it a large territory between the Valais and the lake.
The name Chablais appeared for the first time in 814, under the reign of Louis the Debonair, successor to Charlemagne. Between 888 and 1032 the County of Chablais extended from the lake to Thonon and Vevey and as far as the Trient River on the Valais side.
During this period the Abbey of St-Maurice had total control of the Grand-St-Bernard mountain pass, and owned numerous lands on the plain in the mountains. Gryon, Ollon, their lands and their high mountain pastures were all part of these territories. As of 1032 there were continuous conflicts between the realm of the Bishop of Sion and the Counts of Savoy, who seized the entire territory and extended it farther into Vaud.
During these very unstable periods, a number of communities little by little gained their independence and obtained various rights. The Bernese conquest began in 1475 and was supported as of spring 1476 by allies from the Upper Valais. The Roche castle in Ollon and the St-Triphon castle were burned. In spite of this offensive, the Abbey of St-Maurice retained ownership of its lands and some of its rights until the 18th century. The town of Ollon purchased its rights from the Abbey in 1636 for the sum of 16,500 florins. It remained governed by the lords of the region, only the governor of Aigle was Bernese.
As for Villars, the first traces of activity go back to the 12th and 13th centuries. An intense demographic upsurge motivated the monks from the Abbey of Saint-Maurice to help the peasants who had undertaken a systematic conquest of the mountain pastures. It was precisely at that time that they had considerably expanded the high alpine grass lands. Every mountain pasture conquered and cleared in this manner turned into a real treasure that the peasants passionately defended against the encroachments of their neighbours. Legend has it that the peasants of Ollon were as fierce in defending their mountain pastures in the courts of justice as they were in eradicating invasive alder trees on the pastures. In 1750, the mountain “dixains” (Villars, Chesières, Huémoz) requested to form a separate town, this idea was opposed by the Bernese lords. In 1889, the municipality claimed the archives of the “dixains” in order to add them to those of Ollon; the town became henceforth one indivisible entity