The expanding Roman Empire had annexed the whole of Magna Graecia and Sicily by 241 B.C., and while the Romans planted Latin colonies here and there, on the whole they treated the Italian Greeks as confederates, respecting their language and culture. In Rome itself Greek was employed as a second language and in the first Christian centuries the city had a large Greek-speaking minority. Latin spread through the Greek cities of the South as an administrative language but Greek held its own as a literary medium and the speech of the common people in many areas. At the height of the Empire Vulgar Latin had inplanted itself as the vernacular only as far south as the Apulian towns of Tarentum and Brundisium, and the river Crati in Bruttium (present-day Calabria), the Salentine peninsula, lower Calabria and eastern Sicily remained for the time being strongholds of the Greek language.

In the last centuries of the Empire Latin began to encroach upon literary Greek in Magna Graecia, and it is possible that the Greek vernacular itself might have given way to early Romance had it not been for the Byzantine (= Eastern Roman Empire) conquest of 535. Once Constantinople had replaced Rome as the centre of government, Greek was restored as the official language of southern Italy and Sicily and cultural ties with the Hellenic mainland were reaffirmed. The seventh century saw an influx of Greek-speaking refugees from Syria and Egypt, recently occupied by the Moslems. These immigrants strengthened the reviving Hellenity of the Byzantine Themes (territories) of the South.

Before the coming of the Byzantines, Italian and Sicilian Greek (Italiot), known to the local Italian tribes as Gricus, had been a variant of the Doric (western) dialect of the mainland. The Byzantines now introduced the Neo-Hellenic koine based on the speech of Athens (Attic). The influence transformed the structure of Italiot, though some of the original Doric features survived, and constitute living proof of the unbroken continuity of the Greek language in Italy from ancient times.

Linguistic conditions in Sicily were to be drastically altered by the Saracen invasion of 832. By the tenth century Greek had receded into the south-eastern corner of the island. Then came the Norman conquest of the eleventh century, which struck a serious blow at the roots of Hellenity both in Sicily and on the mainland. The cultural policy of the Normans was ambiguous: while officially tolerating all languages and creeds within their realm they also promoted the use of contemporary south Italian koine (based on the contact language that had evolved in Naples, Amalfi, Salerno and other ports), and favoured the Latin-rite Catholicism of the Holy See, their political ally. The Byzantine Christians among their subjects were severed from the jurisdiction of the Greek Church, by now in schism from Rome, and throughout the kingdom the eastern liturgy began to be replaced by the Roman rite with Latin rather than Greek as the language of worship.

Soon in full decline, the Byzantine rite lingered on in some parishes of the traditional Greek areas of Apulia, Calabria and Sicily until the seventeenth century, when it fell victim of the centralizing policies of the Counter Reformation. From the fourteenth century South Italian began to spread at the expense of Greek in the Messina-Taormina, Milazzo triangle (definitively Italianized by the 1500's) and in southern Calabria and Salento. However there is evidence that Greek continued to be widely spoken in Calabria (at least by the lower classes) until the Renaissance period. The anonymous author of a French chronicle of the late thirteenth century noted that "through the whole of Calabria the peasants speak nothing but Greek". In 1368 Petrarca recommended a stay in the region to a student who needed to improve his knowledge of Greek.

In the early sixteenth century Calabrian Greek was still vigorous in the inland districts south of Palmi and Cittanova but by the close of the seventeenth century it had receded into the Aspromonte mountains of the southern tip of the peninsula, an area comprising hte towns of Cardeto, Bagaladi, Motta San Giovanni, San Lorenzo, Melito, Condofuri, Roghudi, Bova, Palizzi, Africo and Sant'Agata. For the next century and a half the Calabrian Grecia (Greek-speaking zone) remained fairly stable, until the Risorgimento and Unification unleased a new tide of Italian linguisitic influence which accelerated the process of erosion. By the 1920's the ancestral language of South Calabrians could be heard only in the small rural communites of Bova, Amendola, Condofuri, Galliciano, Roccaforte, Roghudi and Ghorio.

Salentine Greek at first declined more rapidly than its Calabrian counterpart. Around 1400 it was already confined to a territorial strip bounded by Gallipoli and the Gulf of Taranto in the west, and Lake Limini near Otranto in the east, with Struda and Alliste as its respective northern and southern limits. By the twentieth century this Grecia had shrunk to a compact district south of Lecce/Luppiu made up of the villages of Calimera, Martignano, Sternatia, Soleto, Zollino, Martano, Castrignano dei Greci, Corigliano and Melpignano.

By the time they became citizens of the Kingdom of Italy in 1861, the Italo-Greeks, mostly poor peasants, had long been severed from the Byzantine religious traditions and from the mainstream of Neo-Hellenic civilization, The modern Italiot renaissance began in the Salentine Grecia through the efforts of Vito Domenico Palumbo (1857 - 1918), a native of Calimera, who endeavoured to re-establish cultural contacts with mainland Greece. Although excluded from the churches, schools and government offices, Greek began to be taught in some villages in the decade following World War II on the initiative of private individuals. In 1971 the Unione dei Greci dell'Italia meridionale was founded to foster relations between the Calabrian Greeks (today numbering only 5,000) and the 15,000 Salentine Greeks. At least three bilingual journals devoted to the Griko language are now in circulation, and a number of mainland Greek intellectuals and cultural bodies have taken an interest in the welfare of their trans-Ionian brothers. Nevertheless, in spite of these developments, Italo-Greek continues to be ignored the the Italian government. Furthermore the Calabrian Grecia, already in an advanced state of decay, suffered a serious setback when the floods of 1970 and 1972 forced the evacuation of Roghudi and Ghorio. The inhabitants of these villages have since been resettled along the Ionian coast and in Reggio where the language has little hope of survival.

Ample traces of the recent Greek past of Calabria, Salento and north-eastern Sicily remain in the local Neo-Italian dialects (the Romance speech that replaced Greek), and in regional surnames like

Argurio ('Silver coin'),
Calabro ('Calabrian'),
Calo, Cala ('good'),
Cefali ('head'),
Chiriaco ('lordly'),
Condro ('fat'),
Dascoli ('Teacher'),
Foti ('bright'),
Lagana ('greengrocer'),
Lico ('wolf'),
Macri ('long'),
Papandrea ('the priest Andrew'),
Patera ('father'),
Pangallo ('very good'),
Schiro ('hard'),
Sgro ('curly-headed'),
Spano ('beardless'),
Trano ('adult'),
Tripodi ('tripod').

The Hellenisms in the modern South Calabrian dialect include such common words as ciaramide 'tile', ahjeri'dish-rag', crasentulu 'worm', capura 'pail', scifu 'trough', tripu 'hole', cudespina 'old woman', cuddaraci 'Easter bun', fusca 'bran', hasmiari 'to yawn', milinghi 'temples', spissida 'spark', cilona 'tortoise', petula 'butterfly', praia 'beach', rosacu 'frog', zafrata 'lizard', and zimmaru 'ram'. South Calabrian offers many examples of Greek syntax in Romance dress, for example the periphrastic construction that replaces the Italian infinitive, e.g. vogghiu mu vajo 'I want to go' (literally: "I want that I go") = Bova Greek thelo na pao (It. Voglio andare), vinni mi ti dugnu 'I came to give you' = irta na su dhosu (It. Venni a darti). Similarly, the use of the preterite tense instead of the Italian present perfect betrays a recent Greek substratum, e.g. comu mangiasti? 'how have you eatern?' = local Greek pos efaje? (It. Come hai mangiato?), ci facistivu? 'what have you done?' = ti ecamete (It. Che cosa avete fatto?).