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,
Flag of Sardinia the arms to a banner given by Pope Benedict VIII to the Pisans in aid of the Sardinians in a conflict with the Saracens of Musetto who were trying to conquer the Italian peninsula and Sardinia. This flag however has inverted colours and no heads on it. Before the Kingdom of Sardinia was founded, the rulers of the island were known as archons (ἄρχοντες in Greek) or judges ("iudices" in Latin, "judikes" in Sardinian, "giudici" in Italian). The island was organized into one "judicatus" from the 9th century on (see List of monarchs of Sardinia). After the Muslim conquest of