Borkou-Ennedi-Tibesti Prefecture was the largest of the 14 prefectures of Chad between 1960 and 1999. It was transformed into Borkou-Ennedi-Tibesti Region, one of the 18 regions into which the country has been divided since 2002. Its name is often abbreviated to BET.Located in the north of Chad it was adjacent to Libya, while also bordering Niger and Sudan. Borkou-Ennedi-Tibesti covered an area of 600,350 km², almost half of Chad's total area.