Conversation so far:
When did the Hellenistic period take place?
The Hellenistic period covers the period of Mediterranean history between the death of Alexander the Great in 323 BC and the emergence of the Roman Empire.
Where were the Illyrian tribes located?
The Illyrians were a group of Indo-European tribes in antiquity, who inhabited part of the western Balkans.
Did the Illyrian tribes have a Ruler/King/President?
Illyria remained in the eastern empire which was later referred to as the Byzantine Empire. The early Byzantine Empire was predominantly ruled by emperors.

Question: Were they peaceful or warlike?
Self-contained rewrite: Were the Illyrians peaceful or warlike?