For the modern municipality, see Orestida
Orestis (Ancient Greek: Ὀρεστίς from the term orestias meaning "mountainous") was a region of Upper Macedonia, corresponding roughly to the modern Kastoria regional unit, West Macedonia, Greece. Its inhabitants were the Greek tribe Orestae who were part of the Molossian tribal state.
Like most of Upper Macedonia, Orestis only became part of Macedon after the early 4th century BC; before that, it had close relations with Epirus. A 6th century BC silver finger ring bearing the frequent Orestian name "Antiochus" was found in the Dodona sanctuary. During the Peloponnesian War, a thousand Orestians led by King Antiochus accompanied the Parauaeans of Epirus. Hecataeus and Strabo identified these mountain kingdoms as being of Epirotic stock. Natives of the region were: Pausanias of Orestis, the lover and murderer of Philip II, and three of Alexander's prominent diadochi: Perdiccas (son of Orontes), Seleucus I Nicator (son of Antiochus) and Craterus, son of a noble from Orestis named Alexander.
The region became independent again in 196 BC, when the Romans, after defeating Philip V, declared the people free because they had adhered to the Roman cause in the recent war against Macedon. According to Appian, Argos Orestikon (in modern Orestida), rather than Peloponnesian Argos, was the homeland of the Argead dynasty.
The Orestians and their tribal neighbours, the Lunkestians, were often mentioned as Illyrians "West of Macedon" until they were assimilated by Philip of Macedon and incorporated in his army and kingdom, they have been mentioned as Highlanders in Ancient Greek recordings, but that is not how they called themselves in their native Illyrian language; unfortunately, most of the writings we possess from that time are from Greek historians and language. That was only after several battles fought against them, with one major battle where more than 7000 Illyrian soldiers were killed. At the same time Philip subdued the Panonians in the North, a population of Illyrian stock.
- John Boardman and Nicholas Geoffrey Lemprière Hammond. The Cambridge Ancient History Volume 3, Part 3: The Expansion of the Greek World, Eighth to Sixth Centuries B.C. Cambridge University Press, 1992, p. 266.
- The Oxford Classical Dictionary, Oxford University Press, 2012, p.966
- Nicholas Geoffrey Lemprière Hammond, Epirus: the Geography, the Ancient Remains, the History and Topography of Epirus and Adjacent Areas, Clarendon Press, 1967, p.703: "The Orestae were Molossian (as we know from a fourth-century inscription)."
- PAAH (1929) 122.
- Appian. Syrian Wars, 11.10.63.