In Greek mythology, Illyrius was the son of Cadmus and Harmonia who eventually ruled Illyria and became the eponymous ancestor of the whole Illyrian people.
The Illyrians are said to have made their appearance on the Balkan peninsula sometime around 1300 BC in the land that would become known as Illyria. The appearance of the Illyrians restrained the Thracians, who until then, were the only northern neighbors of the greeks just to the east.Their lands spanned the coast of the Adriatic and stretched inland, and crossed, the Danube. "Illyrian" tribes, such as the Messapians, are also said to have settled around the eastern shore of Italy. There are even references that show an Illyrian presence in Sicily. For at least the next millennium, they occupied the lands from the Danube, Sava, and Morava rivers to the Adriatic Sea and the Sar Mountains. Illyria was composed of a number of tribes – the Autariatae, Enchelae, Chelidones, Taulanti, etc. – who are considered by scholars to be the Illyrians proper, whereas the many groups to the north – Pannoni, Dalmatae, Liburni, Lapodes – are considered to be a bit distinct from the Illyrians of the south. They are mentioned few times ancient Greek history, one of the first was by Anaximander around the 6th century BC who created a "world map" and included "Illyris" as the territory north-west of Hellenic lands of Epirus and Macedon.