Carbonia-Iglesias is a province in the autonomous region of Sardinia, italy which includes the historical region of Sulcis-Iglesiente, the southwestern part of sardinia.The largest municipalities of the province are the two co-capitals, Carbonia (pop. 30,447 in 2001 census), and Iglesias (28,170). Another important comune is Sant'Antioco (11,730), located on the small island of the same name.