narrow, low-lying plain, about 20 mi (32 km) wide, in southwestern Sardinia, Italy, extending inland about 70 mi (110 km) from the Golfo di (Gulf of) Oristano. It separates Sardinia's small southwestern highland, Iglesiente, from the greater Eastern Highlands, which cover the entire eastern half of the island. Cereal grains, olives, almonds, vegetables, fruit, and grapes for wine are the primary agricultural products. Until 1946 the region was a malarial swamp, but drainage efforts and changed patterns of land use along the course of the Flumini (river) Mannu have made it a populous and fertile region, the chief cities of which include Oristano, a provincial capital, and Terralba.