Ancient land, in what is now northern Greece, the Republic of Macedonia, and western Bulgaria.
Paeonia originally included the whole Vardar River valley. The Paeonians were weakened by the Persian invasion of 490 BC, and the tribes living along the Strymon River fell under Thracian control. The growth of ancient Macedonia forced the remaining tribes north, and they were defeated by Philip II in 358 BC. It became part of the Roman province of Macedonia; by AD 400 the Paeonians had lost their identity and Paeonia was merely a geographic term.