Sardinia has been inhabited since the Paleolithic. The island's most notable civilization is the indigenous Nuragic, which flourished from the 18th century BC to either 238 BC or the 2nd century AD in some parts of the island, and to the 6th century AD in that part of the island known as Barbagia. After a period in which the island was ruled by a political and economic alliance between the Nuragic Sardinians and the Phoenicians, parts of it were conquered by Carthage in the late 6th century BC, and by Rome in 238 BC. The Roman occupation lasted for 700 years. Beginning in the Early Middle Ages, the island was ruled by the Vandals and the Byzantines. In practice, the island was disconnected from Byzantium's territorial influence, which allowed the Sardinians to provide themselves with a self-ruling political organization, the four kingdoms known as Judicates. The Italian maritime republics of Pisa and Genoa struggled to impose political control over these indigenous kingdoms, but it was the Iberian Crown of Aragon which, in 1324, succeeded in bringing the island under its control, consolidating it into the Kingdom of Sardinia. This Iberian kingdom endured until 1718, when it was ceded to the Alpine House of Savoy and later politically merged with the other Savoyard domains on the Italian Mainland. Later, during the period of Italian unification, the Savoyards expanded their domains to include the entire Italian peninsula; their territory was renamed into the Kingdom of Italy in 1861, and it was reconstituted as the present-day Italian Republic in 1946.