To my knowledge, Pannonia was Roman province stretching across today's Hungary, Austria and Croatia. Who were original actually inhabitants of this lands? Was there such thing as Pannonions? Were they Illyrians or related to Illyrians?

Anyway, interesting region. Very old and apparently quite unique looking compared with other parts of Europe.

Celtic tribe Segestani. It was a Celtic-Illyrian tribe basically, they started one of the oldest towns in that region, Siscia or today Sisak. That town was also the capital city of Pannonian Croatian Principally.

Every year there is a festival "Celtic Nights" preformed there
image  :D

I have some family in that town.

It is probably the most fertile land in this part of Central Europe, thus so many wars over it in history…thought originally inhabitants were Illyrians, later Celto-Illyrians after they merged.