East Francia kept a Teutonic core inside a Roman empire
Medieval writers spoke of a Regnum Teutonicum—the Kingdom of Germany—as the Holy Roman Empire's original core beside Italy and Burgundy. It grew from East Francia after Verdun, yet rulers preferred imperial titles; Germany entered official royal style only in 1508.
From 962, German kings claimed the Carolingian imperial dignity and a theoretical universal jurisdiction while still administering distinct Teutonic lands. The Archbishop of Mainz served ex officio as Germany's arch-chancellor. Writers reached for Germania or vernacular labels even when chancery Latin stressed Rome.
Carolingian East Francia from 843 to 911 began the story; Lothair I's death in 855 and the scramble for Lotharingia showed how fragile Verdun's three-way split was. Expansion beyond stem duchies dressed the realm as a transnational empire, but day-to-day power still rested on the German heartland.
Louis the German was already styled Rex Germaniae in his own day, to tell him apart from a brother called King of Gaul, though nobody knows how much the label was meant to carry. When Louis died in 875 his realm split among three sons as Saxony, Bavaria and Swabia, until Charles the Fat reunited it in 882. Big duchies with their own internal loyalty sat inside East Francia; historians count five younger stem duchies, namely Saxony, Bavaria, Franconia, Swabia and Lotharingia, leaving out Thuringia because Saxony had absorbed it in 908. After the last Carolingian, Louis the Child, died in 911, the dukes chose Conrad I as king instead of breaking away. How tribal those duchies really were is disputed: in 1971 Herwig Wolfram rejected any real difference between them and French territorial principalities. A Salzburg annal for 919, known only from a twelfth-century copy, describes Arnulf of Bavaria being elected to reign in a kingdom of the Germans.
Source: Kingdom of Germany
