The Libyan Desert (not to be confused with the Libyan Sahara) is a geographical region filling the north-eastern Sahara Desert, from eastern Libya to the Western Desert of Egypt and far northwestern Sudan. On medieval maps, its use predates today's Sahara, and parts of the Libyan Desert include the Sahara's most arid and least populated regions; this is chiefly what sets the Libyan Desert apart from the greater Sahara. The consequent absence of grazing, and near absence of waterholes or wells needed to sustain camel caravans, prevented Trans-Saharan trade between Kharga (the Darb al Arbein) close to the Nile, and Murzuk in the Libyan Fezzan. This obscurity saw the region overlooked by early European explorers, and it was not until the early 20th century and the advent of the motor car before the Libyan Desert started to be fully explored.