Source: https://www.britannica.com/place/Illyria
Illyria, northwestern part of the Balkan Peninsula, inhabited from about the 10th century BCE onward by the Illyrians, an Indo-European people. At the height of their power, the Illyrian frontiers extended from the Danube Riversouthward to the Adriatic Sea and from there eastward to the Šar Mountains. 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. The last and best-known Illyrian kingdom had its capital at Scodra (modern Shkodër, Albania). One of its most important rulers was King Agron (second half of the 3rd century BCE), who, in alliance with Demetrius II of Macedonia, defeated the Aetolians (231). Agron, however, died suddenly, and during the minority of his son, his widow, Teuta, acted as regent. Queen Teuta attacked Sicily and the coastal Greek colonies with part of the Illyrian navy. Simultaneously, she antagonized Rome, which 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 BCE.