Paeonians were an ancient Indo-European people that dwelt in Paeonia. Paeonia was an old country whose location was to the north of ancient Macedonia, to the south of Dardania, to the west of Thrace and to the east of Illyria, most of their land was in the Axios river basin (called Vardar river by the South Slavs of North Macedonia), roughly in what is today North Macedonia. 
Several eastern Paeonian tribes, including the Agrianes, clearly fell within the Thracian sphere of influence. Some modern scholars consider the Paeonians to have been of either Thracian, or of mixed Thraco-Illyrian origins. However the prevailing scientific opinion is they were of Illyrian stock. Yet, according to the national legend, they were Teucrian colonists from Troy. Homer speaks of Paeonians from the Axios fighting on the side of the Trojans, but the Iliad does not mention whether the Paeonians were kin to the Trojans. Homer calls the Paeonian leader Pyraechmes (parentage unknown); later on in the Iliad (Book 21), Homer mentions a second leader, Asteropaeus, son of Pelagon.
Pausanias described that Paeon, the eponymous ancestor of the Paionians, was a brother of Epeius and Aetolus, the eponymous ancestors of the Epeians of Elis and the Aetolians respectively. According to Irwin L. Merker, this genealogy shows that the Ancient Greeks considered the Paionians to be of Hellenic stock. Their place-name has several cognates in Greece such as (Paeonidai), a deme of the tribe Leontis in Attica. A place in the Argolid also has the same name.
Paeonian is considered a Paleo-Balkan language but this is only a geographical grouping, not a genealogical one. Modern linguists are uncertain as to the classification of Paeonian, due to the extreme scarcity of surviving materials in the language, with numerous hypotheses having been suggested:
The Paeonians included several independent tribes, all later united under the rule of a single king to form the Kingdom of Paeonia.
They worshipped the sun in the form of a small round disk fixed on the top of a pole. They adopted the cult of Dionysus, known amongst them as Dyalus or Dryalus, and Herodotus mentions that the Thracian and Paeonian women offered sacrifice to Queen Artemis (probably Bendis).
Little is known of their manners and customs.
They drank barley beer and various decoctions made from plants and herbs.
The women were famous for their industry. In this connection Herodotus tells the story that Darius, having seen at Sardis a beautiful Paeonian woman carrying a pitcher on her head, leading a horse to drink, and spinning flax, all at the same time, inquired who she was. Having been informed that she was a Paeonian, he sent instructions to Megabazus, commander in Thrace, to deport two tribes of the nation without delay to Asia. An inscription, discovered in 1877 at Olympia on the base of a statue, states that it was set up by the community of the Paeonians in honor of their king and founder Dropion. Another king, whose name appears as Lyppeius on a fragment of an inscription found at Athens relating to a treaty of alliance, is no doubt identical with the Lycceius or Lycpeius of Paeonian coins.
The country of Paeonians had some important resources - it was rich in gold and a bituminous kind of wood (or stone, which burst into a blaze when in contact with water) called tanrivoc (or tsarivos).
Before the reign of Darius Hystaspes, they had made their way as far east as Perinthus in Thrace on the Propontis. At one time all Mygdonia, together with Crestonia, was subject to them. When Xerxes crossed Chalcidice on his way to Therma (later renamed Thessalonica), he is said to have marched through Paeonian territory. They occupied the entire valley of the Axios (Vardar) as far inland as Stobi, the valleys to the east of it as far as the Strymon and the country round Astibus and the river of the same name, with the water of which they anointed their kings. Emathia, roughly the district between the Haliacmon and Axios, was once called Paeonia; and Pieria and Pelagonia were inhabited by Paeonians.
As a consequence of Macedonian power growth, and under pressure from their Thracian neighbors, their territory was considerably diminished, and in historical times was limited to the lands north of Macedonia and from Illyria to the Strymon. In 355-354 BC, Philip II of Macedon took advantage of the death of King Agi of Paeonia and campaigned against them in order to conquer them. So the southern part of ancient Paeonia was annexed by the ancient kingdom of Macedon and was named "Macedonian Paeonia"; this section included the cities Astraion (later Stromnitsa), Stenae (near modern Demir Kapija), Antigoneia (near modern Negotino), etc.
In 280 BC, the Gallic invaders under Brennus ravaged the land of the Paeonians, who, being further hard pressed by the Dardani, had no alternative but to join the Macedonians. Despite their combined efforts, however, the Paeonians and Macedonians were defeated. Paeonia consolidated again but, in 217 BC, the Macedonian king Philip V of Macedon (220-179 BC), the son of Demetrius II, succeeded in uniting and incorporating into his empire the separate regions of Dassaretia and Paeonia. A mere 70 years later (in 168 BC), Roman legions conquered Macedon in turn, and a new and much larger Roman province bearing this name was formed. Paeonia around the Axios formed the second and third districts respectively of the newly constituted Roman province of Macedonia. Centuries later under Diocletian, Paeonia and Pelagonia formed a province called Macedonia Secunda or Macedonia Salutaris, belonging to the Praetorian prefecture of Illyricum.
The Paeonian tribes (five or eight) were: