Migrating Slav tribes appear in the early sixth century on the Balkan borders of the Eastern Roman Empire.

The Slavs at this time owe allegiance to the Avar khans of the Caucasus.

So-called Alpine Slavs or proto-Slovenes, ancestors of the Slovenes, are the first of these Slavic peoples to arrive, migrating southwestward across present-day Romania and pushing up the Sava, Drava, and Mura river valleys into the Eastern Alps and the Karst.

Here, they absorb the existing Romano-Celtic-Illyrian cultures.

The settlement of the Eastern Alps region by early Slavs is part of the southward expansion of the early Slavs that will result in the characterization of the South Slavic group, and will ultimately result in the ethnogenesis of the modern Slovene people.

The Eastern Alpine territories concerned comprise modern-day Slovenia and large parts of modern Austria (Carinthia, Styria, East Tyrol, Lower Austria and parts of Upper Austria).