In the mid-8th century, Carantania became a vassal duchy under the rule of the Bavarians, who began spreading Christianity. Three decades later, the Carantanians were incorporated, together with the Bavarians, into the Carolingian Empire. During the same period Carniola, too, came under the Franks, and was Christianised from Aquileia. Following the anti-Frankish rebellion of Liudewit at the beginning of the 9th century, the Franks removed the Carantanian princes, replacing them with their own border dukes. Consequently, the Frankish feudal system reached the Slovene territory.