The Bosonids were a dynasty of Carolingian era dukes, counts, bishops and knights descended from Boso the Elder. Eventually they married into the Carolingian dynasty and produced kings and an emperor of the Frankish Empire.
The first great scion of the dynasty was Boso V, Count of Arles and of other Burgundian counties in the mid-9th century. Boso rose in favour as a courtier of Charles the Bald. He was even appointed viceroy in Italy in 875. After the death of Charles' son Louis II, Boso refused to recognise both Louis' sons, Carloman and Louis III as kings of France and proclaimed himself King of Provence in 879 at Vienne, with the support of the nobility. Boso strove throughout the rest of his life to maintain his title in the face of the Emperor Charles III. He died in 887 and was succeeded by his son Louis under the regency of his wife Ermengard, a daughter of the Emperor Louis II.
Louis was adopted by Charles III and legitimised in his royal title. With this legal basis, he sought to take the place of his Carolingian relatives on the imperial and Italian thrones in 900. He was crowned in Pavia and then in Rome, but could not actually hold on to power there.