This ancient county covers most of the present-day department of Vaucluse in the area bounded by the Rhône and Durance rivers and by Mont Ventoux. "Venaissin" is derived from the perched town of Venasque, the early capital of the region, whose name itself originates from the roman temple of Venus that existed there.
The history of Provence and the Comtat Venaissin is long and tumultuous. Early tribes traded with Greeks and Phoenecians, aided by the natural navigational routes provided by the Rhône and its tributaries. Carpentras was well established when the Romans conquered the region under Julius Cæsar around 50BC. The post-Roman period was one of great turmoil for the peoples of Provence with invasions by Visogoths, Burgundians and Franks. Some sort of order was restored in 1032 when Provence was annexed by the Holy Roman Empire, allowing towns to grow and prosper. The region was divided up by the Counts of Barcelona and Toulouse in 1125. By that time, Pernes-les-Fontaines had become the capital of the Venaissin region, relatively rich in produce and industry.
In 1274, after a very brief period under the French crown, the Comtat Venaissin was ceded by Philippe III to the Holy See under whose control it remained until the Revolution in 1791, when the county was merged with Avignon to create the department of Vaucluse. The county flourished under the patronage of the Popes who settled in Avignon for most of the next century. Indeed, Clement V first settled in Carpentras where he died in 1314. In 1320, Carpentras became the capital.
The second half of the 14th Cenury was marred by plague and famine, but this was followed by a period of political and economic restoration that was felt throughout France. However, the 16th century was afflicted by religious intollerance punctuated by massacres perpetrated by both sides between the Protestant Vaudois and Huguenots and the largely Catholic peoples of Provence, a conflict that continued for centuries.
The 17th century was a period of great prosperity, followed by blight in rural areas resulting from the failure of silk production and phylloxera that spread through the vineyards. However, irrigation from canals built during the 19th century transformed the countryside into a huge market garden of early fruit and vegetables, brought to market throughout Europe by the new railways. The Comtat Venaissin remains a loose administrative region today, of which Saint Didier is a part, with the constituent towns and villages collaborating in shared services.