Map of France showing the general location of the historical Vexin region.
Map of the Vexin, Beauvoisis, and Hurepoix by Christophe Nicolas Tassin, 1634.

The Vexin (French pronunciation: [vɛksɛ̃]) is a historical county of northwestern France. It covers a verdant plateau on the right bank of the Seine comprising an area east-to-west between Pontoise and Romilly-sur-Andelle (about 20 km before Rouen), and north-to-south between Auneuil and the Seine near Vernon. The plateau is crossed by the Epte and the Andelle river valleys.


The name of the Vexin is derived from a name for a Gaulish tribe now known as the Veliocasses that inhabited the area and made Rouen their most important city.

The Norse nobleman Rollo of Normandy (ca. 846–ca. 931), the first ruler of the Viking principality that became Normandy, made several incursions into the western half of the county. He halted his actions when the Carolingian king Charles III of France, called "Charles the Simple," abandoned the part of the territory that Rollo occupied under the Treaty of Saint-Clair-sur-Epte in 911. The terms of the treaty established the Duchy of Normandy and fixed its boundary with the Kingdom of France along the river Epte. This divided the county of Vexin into two parts:

  • Norman Vexin (Vexin normand), which became part of the Duchy of Normandy bounded by the rivers Epte, Andelle and Seine.
  • French Vexin (Vexin français), which remained part of the Île-de-France province bounded by the rivers Epte, Oise and Seine.


Today, the Vexin is shared by parts of five departments of France: Val-d'Oise and Yvelines in the Île-de-France region; Oise in the Picardie region ; and Eure and Seine-Maritime in the Haute-Normandie region. The major towns are Pontoise, Vernon, Meulan-en-Yvelines, Gisors, and Les Andelys. The plateau is primarily an agricultural region with some manufacturing located in the valleys.

The French Impressionist artists Monet and Van Gogh painted the wheat fields of Vexin.

A regional nature park was established in the French Vexin in 1995.

View of the Vexin region and the Seine river valley from La Roche-Guyon


  •  This article incorporates text from a publication now in the public domainChisholm, Hugh, ed (1911). Encyclopædia Britannica (11th ed.). Cambridge University Press. , re: Normandy.