According to Strabo, Magna Graecia's colonization had already begun by the time of the Trojan War and lasted for several centuries.
In the 8th and 7th centuries BC, for various reasons, including demographic crises (famine, overcrowding, etc.), the search for new commercial outlets and ports, and expulsion from their homeland, Greeks began to settle in southern Italy (Cerchiai, pp. 14–18). Also during that period, Greek colonies were established in places as widely separated as the eastern coast of the Black Sea, Eastern Libya and Massalia (Marseille). They included settlements in Sicily and the southern part of the Italian Peninsula. The Romans called the area of Sicily and the foot of Italy Magna Graecia (Latin, “Great Greece”) since it was so densely inhabited by the Greeks. The ancient geographers differed on whether the term included Sicily or merely Apulia and Calabria: Strabo being the most prominent advocate of the wider definitions.
With colonization, Greek culture was exported to Italy, in its dialects of the Ancient Greek language, its religious rites and its traditions of the independent polis. An original Hellenic civilization soon developed, later interacting with the native Italic civilisations. The most important cultural transplant was the Chalcidean/Cumaean variety of the Greek alphabet, which was adopted by the Etruscans; the Old Italic alphabet subsequently evolved into the Latin alphabet, which became the most widely used alphabet in the world.
Many of the new Hellenic cities became very rich and powerful, like Neapolis (Νεάπολις, Naples, "New City"), Syracuse (Συράκουσαι), Acragas (Ἀκράγας) Paestum (Ποσειδωνία) and Sybaris (Σύβαρις). Other cities in Magna Graecia included Tarentum (Τάρας), Epizephyrian Locri (Λοκροί Ἐπιζεφύριοι), Rhegium (Ῥήγιον), Croton (Κρότων), Thurii (Θούριοι), Elea (Ἐλέα), Nola (Νῶλα), Ancona (Ἀγκών), Syessa (Σύεσσα), Bari (Βάριον) and others.
Following the Pyrrhic War in the 3rd century BC, Magna Graecia was absorbed into the Roman Republic.