The long mining history of Sardinia started probably around the 6th millennium BC with the mining of obsidian at the slant of Monte Arci in the central-eastern part of the island. Monte Arci was one of the most important Mediterranean centres for mining and processing of this volcanic glass in the area. As a matter of fact at least seventy processed hectares of land and about 160 steady or temporary settlements have been found from which obsidian was later exported to Southern France and Northern Italy.