The new province extended from the Gulf of Aulon (Vlorë) and the Acroceraunian Mountains in the north to the lower course of the Acheloos River in the south, and included the northern Ionian Islands of Corfu, Lefkada, Ithaca, Cephallonia, and Zakynthos.

During the third war, the hitherto neutral Epirote League split, with the Molossians siding with the Macedonians and the Chaonians and Thesprotians supporting the Romans.

[6] In the 4th century, Epirus was still a stronghold of paganism, and was aided by Emperor Julian (r. 361–363 AD) and his praetorian prefect Claudius Mamertinus through reduction in taxes and the rebuilding of the provincial capital, Nicopolis.

The Vandals seized Nicopolis in 474 as a bargaining chip in their negotiations with Emperor Zeno, and plundered Zakynthos, killing many of its inhabitants and capturing many others and taking them into slavery.

[8] Procopius of Caesarea claims in his Secret History that under Justinian I (r. 527–565 AD), the entirety of the Balkan provinces was raided by barbarians every year.

[10] In response to these raids, and to repair the damage done by two destructive earthquakes in 522, Justinian initiated a wide-ranging programme of reconstruction and re-fortification: Hadrianopolis was rebuilt, albeit in reduced extent, and renamed Justinianopolis, while Euroea was moved further inland - this has been traditionally identified with the founding of Ioannina.

Thus, in c. 590 the bishop, clergy and people of Euroea fled their city, carrying with them the relics of their patron saint, St. Donatus, to Cassiope in Corfu.

[11] The restoration of Byzantine rule seems to have proceeded from the islands, chiefly Cephallonia, which was certainly under firm Imperial control in c. 702, when Philippicus Bardanes was banished there.

[17] Due to both its traditionally reputed livestock and its proximity to the Italian peninsula, Epirus became a major exporter of cattle and luxury goods like racehorses to Italy, where the latter were in great demand for the popular chariot races in Rome.