stylistic:tone, linguistic:paraphrasing
Middle Ages

In the fifth century, the western half of the Roman Empire collapsed, and the island was invaded by the Vandals and the Ostrogoths. Briefly recovered by the Byzantine Empire, it soon became part of the Kingdom of the Lombards. This made it a dependency of the March of Tuscany, which used it as an outpost against the Saracens. Pepin the Short, king of the Franks and Charlemagne 's father, expelled the Lombards and nominally granted Corsica to Pope Stephen II. In the first quarter of the 11th century, Pisa and Genoa together freed the island from the threat of Arab invasion. After that, the island came under the influence of the Republic of Pisa. Many polychrome churches which adorn the island date from this period. Corsica also experienced a massive immigration from Tuscany, which gave to the island its present toponymy and rendered the language spoken in the northern two-thirds of the island very close to the Tuscan dialect. This led to the traditional division of Corsica into two parts, along the main chain of mountains roughly going from Calvi to Porto-Vecchio: the eastern Banda di dentro, or Cismonte, more populated, developed, and open to the commerce with Italy, and the western Banda di fuori, or Pomonte, almost deserted, wild and remote.

The crushing defeat experienced by Pisa in 1284 in the Battle of Meloria against Genoa had among its consequences the end of the Pisan rule and the beginning of the Genoese influence in Corsica: this was contested initially by the King of Aragon, who in 1296 had received from the Pope the investiture over Sardinia and Corsica. A popular revolution against this and the feudal lords, led by Sambucuccio d'Alando, got the aid of Genoa. After that, the Cismonte was ruled as a league of comuni and churches, after the Italian experience. The following 150 years were a period of conflict, when the Genoese rule was contested by Aragon, the local lords, the comuni and the Pope: finally, in 1450 Genoa ceded the administration of the island to its main bank, the Bank of Saint George, which brought peace.

In the 16th century, the island entered into the fight between Spain and France for supremacy in Italy. In 1553, a Franco-Ottoman fleet occupied Corsica, but the reaction of Spain and Genoa, led by Andrea Doria, reestablished the Genoese supremacy on the island, confirmed by the Peace of Cateau-Cambrésis. The unlucky protagonist of this episode was Sampiero di Bastelica, who would later come to be considered a hero of the island. Their power reinstated, the Genoese did not allow the Corsican nobility to share in the government of the island and oppressed the inhabitants with a heavy tax burden. On the other hand, they introduced the chestnut tree on a large scale, improving the diet of the population, and built a chain of towers along the coast to defend Corsica from the attacks of the Barbary pirates from North Africa. The period of peace lasted until 1729, when the refusal to pay taxes by a peasant sparked the general insurrection of the island against Genoa.

The island became known for the large number of mercenary soldiers and officers it produced. In 1743, over 4,600 Corsicans, or 4% of the entire population of the island, were serving as soldiers in various armies (predominantly those of Genoa, Venice, and Spain), making it one of the most militarized societies in Europe.