Being neither rich in material resources nor well placed for commercial enterprise, Phocis was mainly pastoral. No large cities grew up within its territory, and its chief places were mainly of strategic importance.
The early history of Phocis remains quite obscure. During the Persian invasion of 480 BCE the Phocians at first joined in the national defence, but by their irresolute conduct at the Battle of Thermopylae lost that position for the Greeks; at the Battle of Plataea they were enrolled on the Persian side. In 457 an attempt to extend their influence to the headwaters of the Cephissus in the territory of Doris brought a Spartan army into Phocis in defence of the "metropolis of the Dorians." A similar enterprise against Delphi in 448 was again frustrated by Sparta, but not long afterwards the Phocians recaptured the sanctuary with the help of the Athenians, with whom they had entered into alliance in 454. The subsequent decline of Athenian land power had the effect of weakening this new connexion; at the time of the Peloponnesian War Phocis was nominally an ally and dependent of Sparta, and had lost control of Delphi.
In the 4th century BCE Phocis was constantly endangered by its Boeotian neighbours. After helping the Spartans to invade Boeotia during the Corinthian War (395-94), the Phocians were placed on the defensive. They received assistance from Sparta in 380, but were afterwards compelled to submit to the growing power of Thebes. The Phocian levy took part in the inroads of Epaminondas into Peloponnesus, except in the final campaign of Mantinea (370-62), from which their contingent was withheld. In return for this negligence the Thebans fastened a religious quarrel upon their neighbours, and secured a penal decree against them from the Amphictyonic synod (356). The Phocians, led by two capable generals, Philomelus and Onomarchus, replied by seizing Delphi and using its riches to hire a mercenary army. With the help of these troops the Phocian League at first carried the war into Boeotia and Thessaly, and though driven out of the latter country by Philip of Macedon, maintained itself for ten years, until the exhaustion of the temple treasures and the treachery of its leaders placed it at Philip's mercy. The conditions which he imposed - the obligation to restore the temple funds, and the dispersion of the population into open villages - were soon disregarded. In 339 the Phocians began to rebuild their cities; in the following year they fought against Philip at Chaeronea. Again in 323 they took part in the Lamian War against Antipater, and in 279 helped to defend Thermopylae against the Gauls.
Henceforth little more is heard of Phocis. During the 3rd century BCE it passed into the power of Macedonia and of the Aetolian League, to which in 196 it was definitely annexed. Under the dominion of the Roman republic its national league was dissolved, but was revived by Augustus, who also restored to Phocis the votes in the Delphic Amphictyony which it had lost in 346 and enrolled it in the new Achaean synod. The Phocian League is last heard of under Trajan.