Picardy is one of the oldest provinces of France, and one of the richest too when it comes to the sheer number of historic sites.
As Picardy was never unified in the feudal period, its boundaries are disputable. Linguistically, Picardy extended beyond its geographic boundaries to Artois, Cambrésis, Tournésis, and parts of Flanders and Hainaut; ecclesiastically, it embraced not only the medieval dioceses of Amiens, Noyon, and Laon but also the northern parts of those of Beauvais and of Soissons. The province of Picardy from the 16th century to the end of the ancien régime in 1789 comprised the Somme River basin from Saint-Quentin to the English Channel, the basins of the Serre and of the upper Oise, and Montreuil on the Canche beyond the Authie.
Occupied by the Salian Franks in the 5th century, Picardy was divided in the feudal period and encompassed six countships: Boulogne, Montreuil, Ponthieu, Amiénois, Vermandois, and Laonnois. King Philip II Augustus gradually united Amiénois and Vermandois to his domain (from 1185), but Ponthieu was held by the English as a fief almost continuously from 1279 to 1360 and then as an outright possession until 1369. The dukes of Burgundy acquired Ponthieu, the Somme towns, and Montdidier under the Treaty of Arras in 1435. Reconquered for France by Louis XI in 1477, Picardy was thereafter a frontier area invaded frequently from the Habsburg Netherlands until the French acquisition of Artois and southern Hainaut in 1659.
Some of the bloodiest fighting in World War I occurred in Picardy, reflected in the melancholy English popular song "Roses of Picardy" (1916) and also in the large number of cemeteries that mark former battlefields in the Somme valley. Picardy was also the scene of bitter fighting in World War II—in May 1940 and August and September 1944.