After the Slavic settlement of the Eastern Alps from about 590 and the establishment of the Carantanian principality in the 7th century, the area had fallen under Bavarian suzerainty, when about 740 Prince Boruth asked Duke Odilo for help against invading Avar forces. Incorporated into the Carolingian Empire by Charlemagne, Frankish manoralism was introduced and the northwestern areas were resettled by Bavarian peasants. The population was Christianized by the Archbishops of Salzburg. However, large parts of former Carantania were again lost during the invasion of Hungarian troops culminating in the East Frankish defeat in the 907 Battle of Pressburg.