After the Dorian invasions its became subject to Argos; during the late 7th century BC, a century long dynasty began, under the tyrant Orthagoras, during which the city flourished. This was when its metal work and sculpture reached a high standard, and pottery was also of fine quality. Boutades of Sikyon is believed to have been the originator of the relief form. Kleisthenes, greatest of the kings during the dynasty period joined the Amphiktyonic League in the Sacred War around 590BC, and it was his destruction of the city of Krisa that freed Delphi. He organized the Pythian Games there and started the similar games at Sikyon, abolishing the worship of the Argive here Adrastus. His successor Aeschines was expelled by the Lacedaemonians around 556BC and Sikyon lost its political independence in the Peloponnesian League, but it continued as an important center of both art and industry, and its coinage achieved widespread use during the 5th to 3rd centuries.
During the Persian invasions the Sikyonians were allies of Sparta, as well as during the Peloponnesian War and afterward. The Theban Epaminondas conquered the city in 368BC, though there was a brief revolt during which a citizen seized the government. In 303BC Demetrios Poliorketes (the Besieger) razed the old city and built a new one on the ruins of the old acropolis , naming it for himself (Demetrias). The city became united with the Achaean League in 251BC, under Aratos, son of Kleinias, who later became its leader. After 146 BC and the eclipse of Corinth, Sikyon took over the Isthmian Games, but when Corinth was rebuilt it gradually declined.