Illyria(noun)

an uncertain region on the east shore of the Adriatic where an ancient Indo-European people once lived

Illyria(ProperNoun)

A region in the western part of today's Balkan Peninsula that was inhabited by the Illyrians, ancient Indo-European people.

Illyria

the name anciently given to a broad stretch of mountainous country of varying extent lying E. of the Adriatic Sea. The Illyrians were the last Balkan people to be civilised; becoming a Roman province 35 B.C., Illyria furnished several emperors, among them the notorious Diocletian. Constantine extended the province to include all the country S. of the Danube; at the division of the empire, Greece and Macedonia went to the East, the rest to the West; the name was revived by Napoleon, but has since been dropped.