Lotharii Regnum
During the Merovingian and Carolingian dynasties the Frankish realm was one large kingdom polity subdivided into several smaller kingdoms, often effectively independent. The geography and number of subkingdoms varied over time, but a basic split between eastern and western domains persisted. The eastern kingdom was initially called Austrasia, centred on the Rhine and Meuse, and expanding eastwards into central Europe. Following the Treaty of Verdun in 843, the Frankish Realm was divided into three separate kingdoms: West Francia, Middle Francia and East Francia. In 870, Middle Francia was partitioned again, with most of its territory being divided among West and East Francia, which would hence form the nuclei of the future Kingdom of France and the Holy Roman Empire respectively, with West Francia (France) eventually retaining the choronym.