Magna Graecia (Latin for "Greater Greece," Megalê Hellas/Μεγάλη Ελλάς in Greek) is the name of the area in the southern Italian peninsula that was anciently colonised by Greek settlers in the 8th century BCE, who brought with them the lasting imprint of their Hellenic civilization.

In the 8th and 7th centuries, driven by unsettled conditions at home, Greek colonies were established in places as widely separated as the eastern coast of the Black Sea and what is now Marseille, France. They included settlements in Sicily and the southern part of the Italian peninsula. The Romans called the area of Sicily and the foot of the boot of Italy Magna Graecia (Latin, "Greater Greece"), since it was so thickly inhabited by 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 this colonisation, the Greek culture was exported to Italy, in its dialects of the Ancient Greek language, its religious rites, its traditions of the independent polis but it soon developed an original Hellenic civilisation, later interacting with the native Italic and Latin civilisations. Many of the new cities become very powerful and rich, like Kapuê (Capua), Neapolis (Νεάπολις, Naples), Syracuse, Akragas, Subaris(Σύβαρις, Sybaris). Other cities in Magna Graecia included Taras (Τάρας, Taranto), Lokroi or Locri (Λοκροί), Rhegion (Ρήγιον), Kroton (Κρότων, Crotone), Thurii (Θούριοι) and Elea (Ελαία).

Magna Graecia was absorbed into the Roman Republic following the Pyrrhic War.

During the Early Middle Ages, following the Gothic War that was disastrous for the region, new waves of Byzantine Christian Greeks came to Magna Graecia from Greece and Asia Minor, as southern Italy remained loosely governed by the Eastern Roman Empire until the advent, first of the Lombards then of the Normans. Moreover, without a doubt, the Byzantines found in southern Italy people of common cultural root, the Greek-speaking eredi ellenofoni of Magna Graecia.

Although most of the Greek inhabitants of southern Italy became entirely Italianized (as Paestum had already been in the 4th century BC) and no longer speak Greek, remarkably a small Griko-speaking minority still exists today in Calabria and mostly in Salento. Griko is the name of a language combining ancient Doric Greek, Byzantine Greek, and Italian elements, spoken by people in the Magna Graecia region. There is rich oral tradition and Griko folklore, limited now, though once numerous, to only a few thousand people, most of them having become absorbed into the surrounding Italian element.

Taken from Wikipedia