Fortunately there isn’t much mafia activity here these days even though there is some evidence that suggests the mafia originated in Sardinia

Marlon Brando in The Godfather

There are four main organized crime syndicates in Italy apart from Cosa Nostra - La Stidda (from Sicily), Ndrangheta  (Calabrian Mafia), Sacra Corona Unita (Apulian Mafia) and Mala di Brenta (La Mafia del Brenta). But it is the better known Camorra or Gamurra that allegedly found its birth place in Sardinia. Murra is the Sardinia name given to a form of the game ‘scissor, paper, stone’ that is played religiously all over the island - it even has its own league between villages.
The game originated in China but made its way to Sardinia via Egypt, Greece (there is even an ancient Greek vase depicting Helena and Paris of Troy playing the game) and finally Rome where Roman soldiers coming to the island taught it to the locals. The story goes that the Gamurra first surfaced in the middle ages as a group of military vigilantes in the southern port of Cagliari. It was later taken to Naples in the 1500’s by Sardinian mercenaries thus making it the oldest mafia in the world even pre-dating Sicily’s Cosa Nostra. It is now known as Camorra or the Neapolitan Mafia. 

Fabrizio De André

Anonima Sarda or Anonima Sequestri is the name given to a certain group of people responsible for a lot of the criminal activity on the island including murder, theft and above all kidnapping (they were responsible for the kidnapping of the singer and 'Peoples Poet' Fabrizio De André in 1979). It is not considered to be Mafia or Camorra as it has none of the same organisational traits or hierarchy and is totally disassociated from politics. Instead it lives by a code of honour shared with the bandit population and some of the general population of central Sardinia (Nuoro, Ogliastra Oristano and even parts of the province of Sassari). It is called the Codice Barbaricino.

Extract from the book 'On Another Island' by Malachi Bogdanov