The Duchy of Burgundy was a small portion of the traditional lands of the Burgundians west of the river Saône which, in 843, was allotted to Charles the Bald's kingdom of West Franks. Under the Ancien Régime, the Duke of Burgundy was the premier lay peer of the kingdom of France. Beginning with Robert II of France, the title was held by the Capetians, the French royal family. It was granted to Robert's younger son, Robert, who founded the House of Burgundy. When the senior line of the House of Burgundy became extinct, it was inherited by John II of France through proximity of blood. John granted the duchy to his younger son, Philip the Bold. The Valois Dukes of Burgundy gradually ruled over a vast complex of territories known as the Burgundian State, and became dangerous rivals to the senior line of the House of Valois.