The toponym Carinthia (Slovene: Koroška < Proto-Slavic *korǫt’ьsko) is also claimed to be etymologically related, deriving from pre-Slavic *carantia.

[3] Nowadays, Karantanija is used for the early medieval Slavic principality, while Koroška for the duchy and region that emerged from it from the 10th century onward.

The name, like most toponyms beginning with *Kar(n)- in this area of Europe, are in turn most likely linked to the pre-Roman tribe of the Carni that once populated the eastern Alps.

The few existing historical sources distinguish between two separate Slavic principalities in the Eastern Alpine area: Carantania and Carniola.

[8] Between the 9th and 10th centuries, the Alpine Slavs, who are reckoned to be among the ancestors of present-day Slovenes, settled the eastern areas of the Friuli region.

After Avar rule weakened around 610, a relatively independent March of the Slavs (marca Vinedorum), governed by a duke, emerged in southern Carinthia in the early 7th century.

[6] When about 740 Prince Boruth asked the Bavarian duke Odilo for help against the pressing danger posed by Avar tribes from the east, Carantania lost its independence.

By the 843 Treaty of Verdun, it passed into the hands of Louis the German (804–876) who, according to the Annales Fuldenses (863), gave the title of a "prefect of the Carantanians" (praelatus Carantanis) to his eldest son Carloman.

In the area of Carantania 954–979 exist Slavic parish "pagus Crouuati"(Croats) which is mentioned in royal charters, ruled by count Hartwig in the name of the German king.

The ritual took place on the Prince's Stone (Slovene Knežji kamen, German Fürstenstein), an ancient Roman column capital near Krnski grad (now Karnburg) and was performed in Slovene by a free peasant who, selected by his peers, in the name of the people of the land questioned the new Prince about his integrity and reminded him of his duties.

The core stratum was represented by two groups of Slavs who had settled in the Eastern Alps region in 6th century and are the ancestors of the present-day Slovenes and partially also Austrians.

Other ethnic strong element included the descendants of the Romanised aboriginal peoples (Noricans), which is attestable on the basis of a recent DNA analysis and a number of place names.

Its Proto-Slavic character can be deduced from language contacts of Alpine Slavs with the remainders of the Romanised aboriginal population, later also with Bavarians.