After the disintegration of Samo's realm, Alpine Slavs established the Principality of Carantania in the Eastern Alps, which was independent from around 660 to around 745, when it fell under the Bavarian zone of influence and was later incorporated in the Frankish Empire. Until around 820, it was ruled as a semi-independent tribal polity. After the anti-Frankish rebellion of Ljudevit Posavski, which was partially supported by Carantanians, the Carantanian principality was transformed into a Frankish march, and later emerged as the feudal Duchy of Carinthia.
Carantanians were the first Slavic people to accept Christianity from the West. They were mostly Christianized by Irish missionaries sent by the Archdiocese of Salzburg, among them Modestus, known as the "Apostle of Carantanians". This process was later described in the memorandum known as the Conversio Bagoariorum et Carantanorum, which is thought to have over-emphasized the role of the Church of Salzburg in the Christianization process over similar efforts of the Patriarchate of Aquileia. Several rebellions of the Carantanians against the Christianisations occurred in the late 8th century, which later served as the source of inspiration of the Slovenian Romantic poet France Prešeren in his epic-lyric poem The Baptism on the Savica.
At the beginning of the 9th century, many Carantanians were moved as settlers in the Lower Pannonian region, also known as the Balaton Principality, which was referred in Latin sources as Carantanorum regio or "The Land of the Carantanians".
The name Carantanians (Quarantani) was in use until the 13th century.