Thourioi (Thourium), was a city of Magna Graecia on the Gulf of Tarentum, near the site of the older Sybaris (Italy). It owed its origin to an attempt made in 452 BC by Sybarite exiles and their descendants to re-people their old home. The new settlement was crushed by Croton, but the Athenians lent aid to the fugitives and in 443 BC Pericles sent out to Thourioi a mixed body of colonists from various parts of Greece, among whom were Herodotus and the orator Lysias. 

The pretensions of the Sybarite colonists led to dissensions and ultimately to their expulsion; peace was made with Croton, and also, after a period of war, with Tarentum, and Thourioi rose rapidly in power and drew settlers from all parts of Greece, especially from Peloponnesus, so that the tie to Athens was not always acknowledged. The oracle of Delphi determined that the city had no founder but Apollo, and in the Athenian Expedition in Sicily Thourioi was at first neutral, though it finally helped the Athenians. 

Thourioi had a democratic constitution and good laws, and, though we hear little of its history till in 390 BC it received a severe defeat from the rising power of the Lucanians. Many beautiful coins testify to the wealth and splendor of its days of prosperity. 

In the 4th century BC it continued to decline, and at length called in the help of the Romans against the Lucanians, and then in 282 BC against Tarentum. Thenceforward its position was dependent, and in the Second Punic War, after several vicissitudes, it was depopulated and plundered by Hannibal in 204 BC. 

Thurii ( Ancient Greek : Θούριοι), so called by some Latin writers Thurium (compare Θούριον in Ptolemy ), for a time so Copia and copiae, was a city of Magna Graecia , situated on the Tarentine gulf , within a short distance of the site of Sybaris , Whose place it may be Considered as having taken. The ruins of the city can be found in the Sybaris archaeological park near Sibari in the Province of Cosenza, Calabria, Italy.