The exiled oligarchs appealed to Corcyra while the democrats enlisted the help of Corinth, initiating a struggle between the two mother cities described by Thucydides as a cause of the Peloponnesian War.

Individual trading with the local Illyrians was forbidden at Epidamnos: all traffic was through the authorized city agent or poletes.

[citation needed] In the fourth century BC the city-state was part of the kingdoms of Cassander and Pyrrhus.

Dyrrachium was the landing place for Roman passengers crossing the Ionian Sea from Brundisium, which made it a fairly busy way-station.

In the early 9th century, the province was reorganized as the Theme of Dyrrachium by Emperor Nikephoros I The name "Epidamnus" was still used by the Byzantines, as for example in the 13th-century Synopsis Chronike, referring to contemporary events.