Epirus (ĕpī´rəs), ancient country of Greece, on the Ionian Sea and W of Macedon and Thessaly, a region now occupied by NW Greece and S Albania. At the time of Homer, Epirus was known as the home of the oracle of Dodona. It was inhabited from very early times by Epirote tribes, barely known to the Greeks.
The tribes were molded into a state under the hegemony of one of them (the Molossi), whose chiefs became the paramount rulers in the 4th cent. BC A Molossian ruler, Neoptolemus, married his daughter to Philip II of Macedon, who placed Neoptolemus' son Alexander on the throne of Molossia (most of Epirus). Alexander died on an invasion of Italy, but the kingdom persisted and grew. It reached its height in the 3d cent. BC under Pyrrhus, who achieved great renown. However, Pyrrhus' exploits and the unsuccessful attempts of his successor, Alexander II (d. 240 BC), to take Macedon ruined the state.
A republic was set up with its capital at Phoenice. The Epirotes sided with Macedon in the wars against Rome, and Epirus was sacked (167) by Aemilius Paullus, who took away many thousands of captives. The country passed under Roman dominion. Octavian (later Augustus) built (31 BC) a new capital at Nicopolis.
Epirus was a more-or-less-neglected portion of the Byzantine Empire. After the Crusaders had conquered Constantinople, the despotate of Epirus, larger than ancient Epirus, was set up. At the end of the 18th cent. Ali Pasha, the pasha of Yannina (see Ioánnina), set up an independent state in Epirus and Albania.
See study by N. G. L. Hammond (1967) of the geography and ancient remains of the area.