Deserts are defined as places where only tough plants can grow and provide food for nomadic peoples' hardy sheep. Deserts contain valuable minerals like oil and make up around 3/4 of the land area in the Muslim world. The Sahara desert, which covers 60% of the world's total desert area, is located in Africa. Other major deserts include the Somali desert in Arabia and the Kyzyl and Dasht-e-Lut deserts in Uzbekistan and Iran. Semi-desert and scrub lands receive little rain but not enough for crops, with hot days and cold nights, and crops are eaten by goats and sheep, though their wool is valuable for making carpets in Pakistan