Sybaris had amassed great wealth and a huge population by the sixth century BCE as a result of the rich farming land nearby and its policy of admitting settlers of other nations to its citizenry, a practice shunned by other Greek colonies.

During this period, Sybaris' wealth and power is greatly envied and admired by the rest of the Hellenic world.

It mints its own coinage and its innovations include perhaps the world's first primitive yet effective street-lighting system and the concept of intellectual property.

The latter notion was developed, according to Athenaeus' "Banquet of the Learned" (Deipnosophistae), to ensure that cooks could exclusively profit from their signature dishes for a whole year.

Sybaris is also a dominant power in the region.

We are told by Strabo that the Sybarites ruled over twenty-five subject cities, and could bring into the field three hundred thousand of their own citizens, although this is probably an exaggeration.

Most of the subject cities are probably Oenotrian towns in the interior, but we know that Sybaris had extended its dominion across the peninsula to the Tyrrhenian Sea, where it has founded the colonies of Poseidonia (Paestum), Laüs (Laus), and Scidrus.

The city itself is said to be no less than fifty stadia in circumference, and it is said by Athenaeus that five thousand knights attended its religious processions, which would mean that their number was four times greater than at Athens.

Sybaris is at its height around 580 BCE to 560 BCE during the time of Smindyrides, a prominent citizen who Herodotus claims surpassed all other men in refined luxury.

He is the wealthiest suitor for the daughters of Cleisthenes of Sicyon and was accompanied by a train of one thousand slaves on this occasion.

Athenaeus provides many examples of the opulent wealth for which Sybaris is famous in this period.

In particular, they are renowned for the splendor of their attire, which is made from the finest Milesian wool, and as such have developed extensive commercial relations and a close friendship with Miletus.

Another example of Sybaritic luxury is found in the story of Alcimenes of Sybaris, who gave a splendid figured robe as a votive offering to the temple of Lacinian Juno.

Much later, the robe will fall into the possession of Dionysius of Syracuse and be sold by him for one hundred and twenty talents.

There is very little information on the history of Sybaris after the mid-sixth century until shortly before its fall.

It appears that near the end of the sixth century the government, which had previously been in the hands of an oligarchy, was overthrown by a democratic party headed by a demagogue named Telys who drove a considerable number of the leading citizens into exile.

Subsequently Telys seems to have become the despot or tyrant of the city.

The exiled citizens have taken refuge at Crotona but, not content with their victory, Telys and his partisans demand that the Crotoniats hand over the fugitives.

They refuse to do so and as a result the Sybarites declare war and march upon Crotona with an army said to have amounted to three hundred thousand men.

They are met by the Crotoniats at the river Traeis; the defending army does not amount to more than a third of their numbers.

Nevertheless, the Crotoniats win resoundingly and slaughter most of the Sybarites.

They continue their pursuit to Sybaris' gates, gain control of the city, and determine to raze it to the ground so it can never be inhabited again.

In order to do this, they divert the course of the river Crathis, so that it inundates the site of the city and buries the ruins under its silt deposits.

The surviving inhabitants take refuge at Laüs and Scidrus, on the shores of the Tyrrhenian sea.

This catastrophe occurs in 510 BCE, and seems to have been viewed by many of the Greeks as divine vengeance upon the Sybarites for their pride, arrogance, and excessive prosperity.

More specifically, it is seen as punishment for the contempt they had shown for the great Olympic Games, which they are said to have attempted to supplant by attracting the principal artists and athletes to their own public games.

It is certain that Sybaris was never rebuilt.

Today the site is bare and the exact position of the ancient city cannot be determined.

Explorations undertaken by the Italian government in 1879 and 1887 failed to lead to a precise knowledge of the site.

The municipal building program on the Acropolis continues as Pericles demonstrates Athenian superiority in other ways.

A large Panhellenic colony is founded under Athenian auspices at Thurii, in southern Italy, in 443 BCE.

In this year, or shortly afterwards, Herodotus migrates to Thurium.

Aristotle refers to a version of The Histories written by 'Herodotus of Thurium' and indeed some passages in the Histories have been interpreted as proof that he wrote about southern Italy from personal experience there (IV, 15, 99; VI 127).

The foundation of Thurii, the latest of all the Greek colonies on the Gulf of Taranto, is assigned by Diodorus to the year 446 BCE; but other authorities place it three years later, 443 BCE, and this seems to be the best authenticated date. (Clinton, F. H. vol. ii., p. 54.)

The Athenian-inspired Thurii project represents a fairly substantial mainland Greek encroachment on western soil; this and a mysterious Athenian colonizing effort in the Bay of Naples region, undertaken perhaps in the early 430s by a western expert, Diotimos, must surely cause unease to western-oriented Corinth. (There is even a Spartan aspect: very shortly after its foundation, Thurii is engaged in warfare with Sparta's only historical colony, Taras.)

Thurii does not, however, form a continuing center of Athenian influence in the west, as may have been hoped.

…with the aid of the Lucanians, he devastates the territories of Thurii, …

The expansionist Roman Republic, on the ascendant in the early third century BCE, has spent the 280s suppressing unrest in northern Italy, but Roman attention is soon directed to the far south as well by a quarrel between the Greek city of Thurii and a Samnite tribe.

Thurii calls upon the assistance of Rome, whose naval operations in the area provoke a war with …

Spartacus and his followers seize the town of Thurii and the surrounding countryside, arming themselves, raiding the surrounding territories, trading plunder with merchants for bronze and iron (with which to manufacture more arms), and clashing occasionally with Roman forces which are invariably defeated.

Plutarch makes no further mention of events in the Third Servile War until the initial confrontation between Crassus and Spartacus in the spring of 71 BCE, omitting the march on Rome and the retreat to Thurii described by Appian.

However, as Plutarch describes Crassus forcing Spartacus' followers to retreat southwards from Picenum, one might infer that the rebel slaves approached Picenum from the south in early 71 BCE, implying that they withdrew from Mutina into southern or central Italy for the winter of 72–71 BCE.

Why they might do so, when there was apparently no reason for them not to escape over the Alps—Spartacus' goal according to Plutarch—is not explained.

Despite the contradictions in the classical sources regarding the events of 72 BCE, there seems to be general agreement that Spartacus and his followers were in the south of Italy in early 71 BCE.