Souli is a mountainous region that the Turks never subdued during the Ottoman period, remaining the unbowed refuge of all who refused enslavement. Surrounded by Mts Mournga, Zavrocho and Troulia, it consisted first of four and later of seven villages; at its mid-18th-century heyday it ruled over 80 villages and had some 6,000 inhabitants, 1,700 of them armed. The barrenness of their land led the Souliots to levy taxes on the Ottoman agas, provoking repeated campaigns against them.

Kassope was built by the Thesprotian tribe of the Kassopaians before the mid-4th century BC, to protect the fertile plain from the Elian colonists. It stands on a plateau (approx. 550-650 m) on the north slopes of Mt Zalongo, and was the capital of Kassopaia, with large public buildings and many private residences at its 3rd-century BC heyday. It was surrounded by a polygonal wall about 3.5 m thick.

The Nekromanteion (or Nekyomanteion) of Acheron, the Oracle of the Dead, was the most famous in the ancient Greek world. Archaeological finds — Mycenean shards and a bronze, Mycenean-style sword — indicate that worship of the gods of the Underworld was carried out here from the 14th-13th century BC. The oracle reached its acme in the late 4th and the 3rd-2nd centuries BC, and was destroyed by fire by the Romans in 167 BC.

Nikopolis was built on the Preveza peninsula by Octavian (Augustus) after his victory at the naval battle of Actium against Antony and Cleopatra (31 BC). It was the first Roman colony in Greece, and its first inhabitants were neighbouring peoples forcibly merged from the Epirot cities, Aitoloakarnania and Lefkada.