For some centuries Sicyon remained subject to Argos, whence its Dorian conquerors had come; as late as 500 BC it acknowledged a certain suzerainty. But its virtual independence was established in the 7th century, when a line of tyrants arose and initiated an anti-Dorian policy. Chief of these rulers was the founder's grandson Cleisthenes - the uncle of the Athenian legislator of that name. Besides reforming the city's constitution to the advantage of the Ionians and replacing Dorian cults by the worship of Dionysus, Cleisthenes gained renown as the chief instigator and general of the First Sacred War (590 BC) in the interests of the Delphians.
About this time Sicyon developed the various industries for which it was noted in antiquity. As the abode of the sculptors Dipoenus and Scyllis it gained pre-eminence in woodcarving and bronze work such as is still to be seen in the archaic metal facings found at Olympia. Its pottery, which resembled Corinthian ware, was exported with the latter as far as Etruria. In Sicyon also the art of painting was supposed to have been invented. After the fall of the tyrants their institutions survived till the end of the 6th century, when Dorian supremacy was re-established, perhaps by the agency of Sparta, and the city was enrolled in the Peloponnesian League. Henceforth its policy was usually determined either by Sparta or by its powerful neighbour Corinth.
In the 5th century Sicyon suffered like Corinth from the commercial rivalry of Athens in the western seas, and was repeatedly harassed by flying squadrons of Athenian ships. In the Peloponnesian War Sicyon followed the lead of Sparta and Corinth. When these two powers quarrelled after the peace of Nicias it remained loyal to the Spartans. Again in the Corinthian war Sicyon sided with Sparta and became its base of operations against the allied troops round Corinth. In 369 it was captured and garrisoned by the Thebanss in their successful attack on the Peloponnesian League. During this period Sicyon reached its zenith as a centre of art: its school of painting gained fame under Eupompus and attracted the great masters Pamphilus and Apelles as students; its sculpture was raised to a level hardly surpassed in Greece by Lysippus and his pupils.
The destruction of Corinth (146) brought Sicyon an acquisition of territory and the presidency over the Isthmian games; yet in Cicero's time it had fallen deep into debt. Under the empire it was quite obscured by the restored cities of Corinth and Patrae; in Pausanias' age (A.D. 150) it was almost desolate. In Byzantine times it became a bishop's seat, and to judge by its later name Hellas it served as a refuge for the Greeks from the Slavonic immigrants of the 8th century.
The village of Vasiliko which now occupies the site is quite insignificant.