Middle Francia in the context of "Lotharingia"

East Francia (Latin: Francia orientalis) or the Kingdom of the East Franks (Regnum Francorum orientalium) was a successor state of the Carolingian Empire ruled by the Carolingian dynasty until 911. It was established through the 843 Treaty of Verdun which divided the former kingdom of Francia into three kingdoms: Francia Orientalis (the East Frankish kingdom); Francia Media (the Middle Frankish kingdom); and Francia Occidentalis (the West Frankish kingdom).

The east–west division with the Treaty of Verdun, enforced by the Germanic-Latin language split, "gradually hardened into the establishment of separate kingdoms", with East Francia becoming (or being) the Kingdom of Germany, and West Francia becoming the Kingdom of France.

The Duchy of Burgundy (/ˈbɜːrɡəndi/; Latin: Ducatus Burgundiae; French: Duché de Bourgogne) was a medieval and early modern feudal polity in north-western regions of historical Burgundy. It was a duchy, ruled by dukes of Burgundy. The Duchy belonged to the Kingdom of France, and was initially bordering the Kingdom of Burgundy to the east and south, thus being distinct from the neighboring Free County of Burgundy (modern region of Franche-Comté). The first duke of Burgundy (Latin: dux Burgundiae), attested in sources by that title, was Richard the Justiciar in 918.

In 1004, prince Henry of France, a son of king Robert II of France, inherited the Duchy, but later ceded it to his younger brother Robert in 1032. Robert became the ancestor of the ducal House of Burgundy, a cadet branch of the royal Capet dynasty, ruling over a territory that roughly conformed to the borders and territories of the modern region of Burgundy (Bourgogne). Upon the extinction of the Burgundian male line with the death of Duke Philip I in 1361, the duchy reverted to King John II of France and the royal House of Valois. The Burgundian duchy was absorbed in a larger territorial complex after 1363, when King John II ceded the duchy to his younger son Philip. With his marriage with Countess Margaret III of Flanders, he laid the foundation for a Burgundian State which expanded further north in the Low Countries collectively known as the Burgundian Netherlands. Upon further acquisitions of the County of Burgundy, Holland, and Luxemburg, the House of Valois-Burgundy came into possession of numerous French and imperial fiefs stretching from the western Alps to the North Sea, in some ways reminiscent of the Middle Frankish realm of Lotharingia.

Lothair I (9th. C. Frankish: Ludher and Medieval Latin: Lodharius; Dutch and Medieval Latin: Lotharius; German: Lothar; French: Lothaire; Italian: Lotario; 795 – 29 September 855) was a 9th-century Emperor of the Carolingian Empire (817–855, with his father until 840) and King of Italy (818–855) and Middle Francia (843–855).

Lothair I was the eldest son of the Carolingian emperor Louis I and his wife Ermengarde of Hesbaye, daughter of Ingerman the duke of Hesbaye. On several occasions, Lothair led his full-brothers Pepin I of Aquitaine and Louis the German in revolt against their father to protest against attempts to make their half-brother Charles the Bald a co-heir to the Frankish domains. Upon the father's death, Charles and Louis joined forces against Lothair in a three-year dynastic war (840–843). The struggles between the brothers led directly to the breakup of the Frankish Empire assembled by their grandfather Charlemagne, and laid the foundation for the development of modern France and Germany.

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.

The Treaty of Prüm, concluded on 19 September 855, was the second of the main partition treaties of the Carolingian Empire. As Emperor Lothair I was approaching death, he divided his realm of Middle Francia among his three sons.

The Treaty of Mersen or Meerssen, concluded on 8 August 870, was a treaty to partition the realm of Lothair II, known as Lotharingia, by his uncles Louis the German of East Francia and Charles the Bald of West Francia, the two surviving sons of Emperor Louis I the Pious. The treaty followed an earlier treaty of Prüm which had split Middle Francia between Lothair I's sons after his death in 855.

The treaty is referred to in some Western European historiographies as the third major partition of Francia, all of which took place from August 843 to August 870, through the treaties of Verdun, Prüm and Mersen. It was followed by the Treaty of Ribemont.

Upper Burgundy (Latin: Burgundia superior; French: Bourgogne supérieure) was a historical region in the early medieval Burgundy, and a distinctive realm known as the Kingdom of Upper Burgundy, that existed from 888 to 933, when it was incorporated into the reunited Kingdom of Burgundy, that lasted until 1032. During those periods, the region of Upper Burgundy was encompassing the entire Juran Burgundy (French: Bourgogne jurane), including the County of Burgundy (modern region of Franche-Comté). The Kingdom of Upper Burgundy was established in 888 by the Welf king Rudolph I within the territory of former Middle Francia. Under his son and successor, king Rudolph II, Upper Burgundy was reunited with Lower Burgundy in 933 to form the Kingdom of Burgundy, that existed until 1032.