Epirus (//) is a geographical and historical region in southeastern Europe, now shared between Greece and Albania. It lies between the Pindus Mountains and the Ionian Sea, stretching from the Bay of Vlorë and the Acroceraunian Mountains in the north to the Ambracian Gulf and the ruined Roman city of Nicopolis in the south. It is currently divided between the region of Epirus in northwestern Greece and the counties of Gjirokastër, Vlorë, and Berat in southern Albania. The largest city in Epirus is Ioannina, seat of the region of Epirus, with Gjirokastër the largest city in the Albanian part of Epirus.
A rugged and mountainous region, Epirus was the north-west area of ancient Greece. It was inhabited by the Greek tribes of the Chaonians, Molossians, and Thesprotians. It was home to the sanctuary of Dodona, the oldest oracle in ancient Greece, and the second most prestigious after Delphi. Unified into a single state in 370 BC by the Aeacidae dynasty, Epirus achieved fame during the reign of Pyrrhus of Epirus who fought the Roman Republic in a series of campaigns. Epirus subsequently became part of the Roman Republic along with the rest of Greece in 146 BC, which was followed by the Roman Empire and Eastern Roman Empire.
Following the fall of Constantinople to the Fourth Crusade, Epirus became the center of the Despotate of Epirus, one of the successor states to the Byzantine Empire. Conquered by the Ottoman Empire in the 15th century, Epirus became part of the semi-independent Pashalik governed by the Ottoman Albanian ruler Ali Pasha in the early 19th century, but the Sublime Porte re-asserted its control in 1821. Following the Balkan Wars and World War I, southern Epirus became part of Greece, while northern Epirus became part of Albania.
The name Epirus is derived from the Greek: Ἤπειρος, romanized: Ḗpeiros (Doric Greek: Ἄπειρος, romanized: Ápeiros), meaning “mainland” or terra firma. It is thought to come from an Indo-European root *apero- ‘coast’, and was applied to the mainland of north-west Greece opposite Corfu and the Ionian islands. The local name was struck on the coinage of the unified Epirote commonwealth: “ΑΠΕΙΡΩΤΑΝ” (Ancient Greek: Ἀπειρωτᾶν, romanized: Āpeirōtân, Attic Greek: Ἠπειρωτῶν, romanized: Ēpeirōtôn, i.e. “of the Epirotes”, see image right). The Albanian name for the region, which derives from the Greek, is Epiri. Similarly, the Aromanian name for Epirus, which is also Greek-derived, is Epiru.