Arnulf of Carinthia (German Arnulf von Kärnten, Slovenian Arnulf Koroški) (850 - December 8 899) was one of the last ruling members of the Carolingian house in the Eastern part of the Frankish Kingdom, which had been split in the Treaty of Verdun in 843.
Upon the deposition of his uncle, the emperor Charles III the Fat, Arnulf assumed his title of King of the East Franks in 887. Soon after his election for a king the term Karantania became a new European political term.
In Carinthia Carloman had a court in Moosburg (Blatograd), where young Arnulf spent his childhood. From later events it is evident that the Karantanians treated him as their own duke.
Arnulf didn't negotiate but he fought. At the decisive Battle of Leuven on September 891 he defeated an invading force of the Northmen, or Vikings, essentially ending invasion attempts on that front and the kingdom. After his victory, Arnulf had built a new castle on an island in the Dijle river (Latin Luvanium, local Lovon). The Annales Fuldensis (Annals of Fulda) report that the bodies of dead Northmen blocked the run of the river.