Sardinia world (22 centenarians/100,000 inhabitants). Sardinia is the first discovered Blue Zone, a demographic and/or geographic area in the world with an oversize concentration of centenarians and supercentenarians. In 2016 there were 50,346 foreign national residents, forming 3% of the total Sardinian population. The most represented nationalities were: Sardinia's most populated cities are Cagliari and Sassari. The Metropolitan City of Cagliari has 431,302 inhabitants, or about ¼ of the population of the entire island. Eurostat has identified in Sardinia two Functional Urban Areas: Cagliari, with 477,000 inhabitants, and Sassari, with 222,000 inhabitants. Sardinia is one of the five Italian autonomous regions,
Sardinia occupied the territory. The Giudicato of Arborea, having Oristano as its capital, had the longest life compared to the other kingdoms. Its later history is entwined with the attempt to unify the island into a single Sardinian state ("Republica sardisca" "Sardinian Republic" in Sardinian, "Nació sarda" or "sardesca" "Sardinian Nation" in Catalan) against their relatives and former Aragonese allies. In 1297, Pope Boniface VIII established on his own initiative ("motu proprio") a hypothetical "regnum Sardiniae et Corsicae" ("Kingdom of Sardinia and Corsica") in order to settle the War of the Sicilian Vespers diplomatically. This had broken out in 1282 between