The map visualises how the Treaty of Verdun (843) split the Carolingian Empire created by Charlemagne into three separate kingdoms, each ruled by a son of the late Emperor Louis the Pious. The treaty ended a bitter civil war among Charlemagne’s grandsons and set the cultural fault-lines, which would later solidify into France (purple), Germany (yellow), and a short-lived Middle Kingdom (blue).

More specifically:

Western kingdom – Francia occidentalis (purple)

• Core Frankish heartland “Francia” stretching from Rouen and Paris down to Tours and Bourges.
• Southern marches: Aquitaine, Gascony, Septimania, Spanish March/Navarre guarding the Pyrenees.
• Atlantic seaboard cities: Brest, Nantes, Bordeaux.
• Roughly anticipates the later medieval kingdom of France.

Middle kingdom – Francia media (blue)

• Northern belt Lotharingia (Aachen, Utrecht, Mainz) linking North Sea to the Alps.
• Central Burgundy (Besançon, Lyon, Geneva) and Provence (Arles, Marseille).
• Italian axis: Kingdom of Italy—Milan, Ravenna, Venice—and the Alpine corridor down to Rome (Papal States remain grey and independent).
• A long, corridor-shaped realm intended to give the emperor sea-to-sea control.

Eastern kingdom – Francia orientalis (yellow)

• Germanic stem-duchies: Saxony (Hamburg, Bremen), Thuringia, Franconia, Swabia (Ulm, St Gall), Bavaria, Carinthia.
• Eastern frontier faces the Moravian Kingdom and Slavic lands; Prague lies just beyond the red border.
• Foreshadows the later Holy Roman Empire’s German core.

Map take-aways

• The single Carolingian Empire has been carved into three colour-coded kingdoms, each following major ethnic and geographic blocs.
• Internal frontiers run north–south, while the outer imperial border (red) still encircles much of Western Europe.
• Lothair’s elongated middle strip—linking the North Sea to central Italy.