Carantania's capital was most likely Karnburg (Slovene: Krnski grad) in the Zollfeld Field (), north of modern-day town of Klagenfurt ().
The borders of the later Carantania state, which was under the feudal overlordship of the Carolingians, and its successor (the March of Carinthia, 826-976), as well as of the later Duchy of Carinthia (from 976), extended beyond historical Carantania.