Lower Burgundy is sometimes called the Kingdom of Arelat, the Kingdom of Cisjurane Burgundy, or the Kingdom of Provence.

The borders of Lower Burgundy are the Mediterranean Sea to the south, Septimania to the southwest, Aquitaine to the west, the Kingdom of Upper Burgundy to the north, and the Kingdom of Italy to the east.

Louis the Stammerer, who dies on April 10, 879, is survived by two adult sons, Louis and Carloman.

Boso renounces allegiance to both brothers and in July claims independence of the Kingdom of Provence.

On 15 October 879, the bishops and nobles of the region around the rivers Rhône and Saône assemble in the Synod of Mantaille and elect Boso king as successor to Louis the Stammerer, the first non-Carolingian king in Western Europe in more than a century.

This is the first "free election" of a king among the Franks, without regard to royal descent, though his mother was a Carolingian.

The Kingdom comprises the ecclesiastical provinces of the archbishops of Arles, Aix, Vienne, Lyon (without Langres), and probably Besançon, as well as the dioceses of Tarentaise, Uzès, and Viviers.