The Illyrians, bearers of the Hallstatt culture, were divided into tribes, each a self-governing community with a council of elders and a chosen leader. A strong tribal chieftain, however, could unite several tribes into a kingdom. One of its most important rulers was King Agron (second half of the 3rd century BC), who, in alliance with Demetrius II of Macedonia, defeated the Aetolians (231).
Agron, however, died suddenly of enjoying too much alcohol and during the minority of his son, his widow, Teuta, acted as regent. Queen Teuta attacked Sicily and the Greek colonies on the coast with part of the Illyrian navy. Simultaneously, she antagonized Rome. Before starting the war Greeks and Romans send their emissaries to Queen Teuta asking her to order her sailors to stop pirating their merchant boats and vilages. But Queen Teuta replied that she could not stop her people collecting the fruits of the sea. So the Romans finally sent a large fleet to the eastern shores of the Adriatic.
Although Teuta submitted in 228, the Illyrian kingdom of the interior was not destroyed, and a second naval expedition was sent against Illyria in 219. Philip V of Macedonia aided his Illyrian neighbours and thus started a protracted war that ended with the conquest of the whole Balkan Peninsula by the Romans. The last Illyrian king, Genthius, surrendered in 168 BC. The Roman province of Illyricum stretched from the Drilon River (the Drin, in modern Albania) in the south to Istria (modern Slovenia and Croatia) in the north and to the Savus (Sava) River in the east; its administrative centre was Salonae (near present-day Split) in Dalmatia. With the extension of the Roman Empire along the Danube River valley, Illyricum was divided between the provinces of Dalmatia and Pannonia. Under the empire Illyria enjoyed a high degree of prosperity. It was traversed by a Roman road, and Illyria's ports served as important trade and transit links between Rome and what is now eastern Europe. Copper, asphalt, and silver were mined in parts of the region, and Illyrian wine, oil, cheese, and fish were exported to Italy.