oasis group about 30 miles (48 km) long and 12 miles (19 km) wide in southeastern Libya, in an elliptical trough near the centre of the Libyan Desert. Astride ancient caravan routes, the oasis was a raiders' stronghold until 1895, when it became the headquarters of the Sanūsī, a reformist Muslim religious fraternity. The Italians launched an aerial offensive against the oasis, the last haven of the Sanūsī, in 1930 and occupied it in 1931.

The main towns are Al-Jawf, Al-Ṭulaylīb, and Al-Ṭallāb; Al-Ṭāj, on a sandstone plateau, has a Sanūsī religious school. There are extensive date groves, and an underground reservoir provides irrigation. Livestock raising is important. Pop. (2005 est.) 56,356.