Lower Burgundy in the context of "King of Provence"

In medieval historiography, West Francia (Medieval Latin: Francia occidentalis) or the Kingdom of the West Franks (Latin: regnum Francorum occidentalium) constitutes the initial stage of the Kingdom of France and extends from the Treaty of Verdun in 843 to 987, the beginning of the Capetian dynasty. It was created from the division of the Carolingian Empire following the death of Louis the Pious, with its neighbor East Francia eventually evolving into the Kingdom of Germany.

West Francia extended further north and south than modern metropolitan France, but it did not extend as far east. It did not include such future French holdings as Lorraine, the County and Kingdom of Burgundy (the duchy was already a part of West Francia), Alsace and Provence in the east and southeast for example. It also did not include the Brittany peninsula in the west.

The land of Provence has a history quite separate from that of any of the larger nations of Europe. Its independent existence has its origins in the frontier nature of the dukedom in Merovingian Gaul. In this position, influenced and affected by several different cultures on different sides, the Provençals maintained a unity which was reinforced when the region was made a separate kingdom during the Carolingian decline of the later ninth century. When Boso of Provence acquired the region in 879, it was known as Lower Burgundy until it was merged with Upper Burgundy in 933 to form the Kingdom of Arles. The counts of Arles began calling themselves "count of Provence"; although in name vassals, they were de facto autonomous princes. After 1032, the county was part of the Holy Roman Empire.

In the eleventh century, Provence became disputed between the traditional line and the counts of Toulouse, who claimed the title of "Margrave of Provence". In the High Middle Ages, the title of Count of Provence belonged to local families of Frankish origin, from 1112 to 1245 to the House of Barcelona (a cadet branch of the House of Aragón), from 1245 to 1382 to the House of Anjou, and from 1382 to 1481 to a cadet branch of the House of Valois. It was inherited by King Louis XI of France in 1481, and definitively incorporated into the French royal domain by his son Charles VIII in 1487.

The Kingdom of Burgundy (Latin: Regnum Burgundiae), also known as the Kingdom of Arles (Latin: Regnum Arleatense), was a realm established in 933 by the unification of Lower Burgundy with the Upper Burgundy. As an independent kingdom, it was ruled by monarchs from the Elder House of Welf until 1032, when it was incorporated into the Holy Roman Empire, becoming one of the empire's three constituent realms, together with the Kingdom of Germany and the Kingdom of Italy. By the 13th century it went through the process of feudal fragmentation, and since the 14th century the imperial rule over the kingdom became mainly nominal, weakening further during the 15th century.

Its territory stretched from the Mediterranean Sea in the south to the High Rhine in the north, and from the Western Alps in the east to the Rhône basin in the west, thus encompassing almost all of the historical Burgundian lands, and roughly corresponding to the present-day French regions of Provence-Alpes-Côte d'Azur, Rhône-Alpes and Franche-Comté, as well as the region of Romandy in western Switzerland.

Lothair II (835 – 8 August 869) was a Carolingian king and ruler of northern parts of Middle Francia, that came to be known as Lotharingia, reigning there from 855 until his death in 869. He also ruled over Burgundy, holding from 855 just the Upper regions, and from 863 also the Lower Burgundy. He was the second son of Emperor Lothair I and Ermengarde of Tours. He was married to Teutberga (died 875), daughter of Boso the Elder.

Boso of Provence (French: Boson; c. 841 – 11 January 887) was the first non-Carolingian pretender to the royal throne of West Francia in 879, who failed to achieve wider recognition, being accepted only in Lower Burgundy and Provence, where he ruled as king from 879 to 887. By 882, he had already lost much of his Burgundian domains, and had to retreat to his remaining possessions in Provence. By ancestry, he was a Frankish nobleman of the Bosonid family, who was related to the Carolingian dynasty and previously served as a count in several south-eastern counties of the West Frankish realm.

In historiography, he is styled as King of Burgundy or King of Provence.

Middle Francia (Latin: Francia media) was a short-lived Frankish kingdom which was created in 843 by the Treaty of Verdun after an intermittent civil war between the grandsons of Charlemagne resulted in division of the united empire. Middle Francia was allocated to Emperor Lothair I, the eldest son and successor of Emperor Louis the Pious. His realm contained the imperial cities of Aachen (the residence of Charlemagne) and Pavia, but it lacked any geographic or cultural cohesion, which prevented it from surviving and forming a nucleus of a larger state, as was the case with West Francia (which became the Kingdom of France) and East Francia (which became the Kingdom of Germany).

Middle Francia was situated between the realms of East and West Francia and comprised the Frankish territory between the rivers Rhine and Scheldt, the Frisian coast of the North Sea, the former Kingdom of Burgundy (except for a western portion, later known as Bourgogne) and Provence, as well as parts of northern Italy. Following the 855 partition, 'Middle Francia' became only a geographic term, and the bulk of its territory was reorganised as Lotharingia, named after Lothair I's namesake son. One of the reasons Middle Francia was a short-lived state was its geographic situation between two more powerful states, each of which had much greater influence in Europe than Middle Francia.