The Western Desert is located within the Libyan Desert, in the northern and eastern part of the Sahara Desert, comprising the desert of Western Egypt, Eastern and Southern Libya, and Northwestern Sudan. The Egyptian portion is called the Western Desert, from the perspective of the Nile Valley. It comprises the New Valley Governorate and the interior part of the Matrouh Governorate. Covering an area of approximately 1,100,000 km², this vast space extends approximately 1100 km from east to west, and 1,000 km from north to south, in about the shape of a rectangle. Like most of the Sahara, this desert is primarily sand and hamada or stony plain. Sand plains, dunes, ridges and some depressions (basins) typify the region, and no rivers drain into or out of the area.
In most of Upper Egypt, the desert encroaches very near the Nile, with a flood plain only a few kilometers wide. The Siwa Oasis, close to the Libyan border and west of Qattara, is isolated from the rest of Egypt but has sustained life since ancient times. The other major oases include Dakhla and Kharga in Egypt, and Jaghbub and Kufra in Libya. Apart from Kufra they form a topographic chain of basins extending from Al Fayyum (sometimes called the Fayyum Depression) which lies sixty kilometers southwest of Cairo, south to the Bahariya, Farafra and Dakhla oases before reaching the country's largest oasis, Kharga Oasis. A brackish lake, Lake Karun, at the northern reaches of Al Fayyum, drained into the Nile in ancient times. For centuries sweetwater artesian wells in the Fayyum Oasis have permitted extensive cultivation in an irrigated area that extends over 2,100 km².