Epirus has been occupied since Neolithic times, when hunters and shepherds inhabited the region and constructed large tumuli to bury their leaders. The tumuli had many similar characteristics to those later used by the Myceneans, suggesting a possible ancestral link between Epirus and the Mycenean civilisation. Certainly, Mycenean remains have been found at two ancient religious sites in the region, the Necromanteion (Oracle of the Dead) on the Acheron river, and the Oracle of Zeus at Dodona.
The Dorians invaded Greece via Epirus and Macedonia at the end of the 2nd millennium BC (circa 1100 BC-1000 BC), though the reasons for their migration are obscure. The region's original inhabitants were driven southward into the Greek mainland by the invasion and by the early 1st millennium BC three principal clusters of Greek-speaking tribes had emerged in Epirus. These were the Chaones of northwestern Epirus, the Molossians in the centre and the Thesprotians in the middle.These were the Tribes of Epirus.
Unlike most other Greeks of the time, who lived in or around city-states such as Athens or Sparta, the Epirotes lived in small villages. Their region lay on the edge of the Greek world and was far from peaceful; for many centuries, it remained a frontier area contested with the Illyrian peoples of the Adriatic coast and interior. However, Epirus had a far greater religious significance than might have been expected given its geographical remoteness, due to the presence of the shrine and oracle at Dodona - regarded as second only to the more famous oracle at Delphi.
The Epirotes seem to have been regarded with some disdain by the Athenians when the latter rose to power, a fate suffered by many Greek enemies of Athens or those Greeks they considered culturally inferior to themselves.The 5th century BC Athenian historian Thucydides describes them as "barbarians" and the only Epirotes regarded as truly Greek were the Aeacidae, who claimed to be descended from Neoptolemus, son of Achilles. As well Strabo says: "and even to the present day the Thracians, Illyrians, and Epeirotes live on the flanks of the Greeks (though this was still more the case formerly than now); indeed most of the country that at the present time is indisputably Greece is held by the barbarians — Macedonia and certain parts of Thessaly by the Thracians, and the parts above Acarnania and Aetolia by the Thesproti, the Cassopaei, the Amphilochi, the Molossi, and the Athamanes — Epeirotic tribes." In opposite, other ancient Greek and Roman writers such as Apollodorus, Dionysius of Halicarnassus, Frontinus, Pausanias, Ptolemy, Cassius Dio and Eutropius, describe them as Greeks. Plutarch mentions an interesting cultural element of the Epirotes regarding Achilles. In his biography of king Pyrrhus, he claims that Achilles "had a divine status in Epirus and in the local dialect he was called Aspetos". The Aeacidae established the Molossian dynasty, who built a state in Epirus from about 370 BC onwards, expanding their power at the expense of rival tribes. The Molossians allied themselves with the increasingly powerful kingdom of Macedon and in 359 BC the Molossian princess Olympias, niece of Arybbas of Epirus, married King Philip II of Macedon. She was to become the mother of Alexander the Great.
On the death of Arybbas, Alexander of Epirus succeeded to the throne and the title King of Epirus. Aeacides of Epirus, who succeeded Alexander, espoused the cause of Olympias against Cassander, but was dethroned in 313 BC. His son Pyrrhus came to throne in 295 BC, and for six years fought against the Romans in southern Italy and Sicily. His campaigns gave Epirus a new, but brief, importance and a lasting contribution to the language with the concept of a "Pyrrhic victory".
In the 3rd century BC Epirus remained a substantial power, unified under the auspices of the Epirote League as a federal state with its own parliament (or synedrion). However, it was faced with the growing threat of the expansionist Roman Republic, which fought a series of wars with Macedonia. The League remained neutral in the first two Macedonian Wars but split in the Third Macedonian War (171 BC-168 BC), with the Molossians siding with the Macedonians and the Chaones and Thesproti siding with Rome. The outcome was disastrous for Epirus; Molossia fell to Rome in 167 BC, 150,000 of its inhabitants were enslaved and the region was so thoroughly plundered that it took 500 years for central Epirus to recover fully.
The Treaty of Berlin of 1881 gave Greece parts of southern Epirus, but it was not until the Balkan Wars of 1912-13 that the rest of southern Epirus joined Greece. Northern Epirus was awarded to Albania by an international boundary commission. This outcome was unpopular among both Greeks and Albanians, as settlements of the two people existed on both sides of the border. Among Greeks, northern Epirus was regarded as terra irredenta.
When World War I broke out in 1914 , Albania collapsed. Under a March 1915 agreement among the Allies, Italy seized northern Albania and Greece set up an autonomous Greek state of North Epirus in the southern part of the country. Although short-lived, the state of North Epirus managed to leave behind a number of historical records of its existence, including its own postage stamps; see Postage stamps and postal history of Epirus.
Although the Paris Peace Conference of 1919 awarded the area to Greece after World War I, political developments such as the Greek defeat in the Greco-Turkish War and, crucially, Italian, Austrian and German lobbying in favour of Albania meant that Greece, although backed by Russia, could not claim northern Epirus. The area was finally ceded to Albania in 1924.
Italy occupied Albania in 1939 and in 1940 invaded Greece. The Italians were, however, driven back into Albania and Greece again took control of northern Epirus. The conflict, known as the Greco-Italian War, marked one of the first tactical victories of the Allies in World War II. Mussolini himself supervised the massive counter-attack of his divisions in spring 1941 , only to be decisively defeated again by the poorly equipped, but determined, Greeks. Nazi Germany intervened in April 1941 to avert an embarrassing Italian defeat. The German military performed rapid military maneuvers through Yugoslavia and forced the encircled Greek forces to surrender.
The whole of Epirus was then placed under Italian occupation until 1943 , when the Germans took over following the Italian surrender to the Allies. The highlands of Epirus became the major theatre of guerrilla inter-fighting between the communist National People's Liberation Army (ELAS) and the republican National Republican Greek League (EDES). Following the German withdrawal from Greece in 1944 , the mountains of Epirus became the scene of some of the fiercest fighting of the Greek Civil War.
It was during this time that Cham Albanians were forced out of Greek Epirus; members of the Cham community had collaborated with the Axis forces during the occupation of Greece, and when the Cham bands declined EDES' request to help them against ELAS, the former, with British support, attacked Cham villages killing 5,000 civilians and forcing about 35,000 to flee.
The current President of the Hellenic Republic, Karolos Papoulias, is a native of Ioannina, Epirus.