Commerce.—From the earliest times Saharan commerce has been the monopoly of the nomad peoples. Salt and ivory were carried across the desert in very early times. In the middle ages the Jews possessed great influence in this part of Africa as or ganizers of trade. In 1447 the Genoese merchant traveller, An tonio Malfaute, visited the Oasis of Tuat and pointed out its importance as a trade centre between the Muslim countries sur rounding the desert. He mentions the large quantities of copper carried south to the negro kingdoms of the Sudan, and the vege table butter there produced. There is evidence that the Venetians and Genoese both had considerable interests in African trade.
Salt and date palms are the chief products of the Sahara at the present time. The principal sources of the salt supply are the rock salt deposits of the Juf (especially Taudeni), the lakes of Kufara and the rock salt and brine of Bilma (q.v.).
Trade routes run (I) from Morocco to Cairo by Insalah and Ghadames, the route of West African pilgrims to Mecca, now largely superseded by the sea route from Tangier to Alexandria; (2) from Kuka (Lake Chad) to Murzuk and Tripoli; (3) from Kano and Zinder to Tripoli by Air and Ghat ; (4) from Timbuktu to Insalah, Ghadames and Tripoli; (5) from Timbuktu to Insalah and thence to Algeria and Tunisia; (6) from Algeria—through Tuat and Timbuktu to the Niger. The Senussi movement brought into prominence the desert routes between Wadai in the south and Jalo and Benghazi in the north, which partially superseded some of the older routes. The long-established route from Darfur to the Kharga and Dakhla oases fell into disuse on the closing of the eastern Sudan by the Mandist troubles. The great route leading from Tripoli via Ghadames and Ghat, to Zinder, Kano, and other great centres of the Hausa States maintains its importance, but the opening of trade from the side of the Niger by the British in the early years of the loth century affected its value. The route across the western Sahara to Timbuktu is less used than formerly owing to the establishment by the French of a route from Senegal via Nioro to the Upper Niger. The old route, however, retains some importance on account of the salt trade from the Sahara, which centres at Timbuktu.
Railway Schemes.—Two principal routes for a railway across the desert have been suggested, the one taking an easterly line from Biskra through Warqla to Air (Agades) and Zinder, the other starting from the terminus of the most westerly railway already existing, and reaching Timbuktu via Igli and the Tuat oases. A third suggested route is one from Igli to the Senegal, still farther west.
Political Divisions.—The western Sahara, in the main, is ad ministered within French West Africa while the eastern regions of the desert fall into Italian Libya, Egypt and Anglo-Egyptian Sudan. The French first acquired an interest in the Sahara by their conquest of Algiers (183o-45). They gradually extended their influence southward with the purpose of forming a junction with their possessions on the Senegal. The acquisition of Tunisia (1881) largely increased the hold of the French on the Sahara, and the work of French pioneers to the south of Algeria was recognized by the Anglo-French agreement of 189o, which as signed to France the whole central Sahara from Algeria to a line from Say, on the Niger, to Lake Chad. The southern limit of the
territory was, however, not strictly defined until 1898, when a new agreement gave to France a rectangular block south of the line mentioned, including the important frontier town of Zinder. A further agreement in 1904 again modified the frontier in favour of France. To the north-east and east the boundary of the French sphere was made to run south-east from the intersection of 231° N. with 16° E., following this south to the western frontier of Darfur and the Anglo-Egyptian Sudan. French Sahara is thus connected with the French possessions in West Africa and with the Congo-Shari territories of France on the south-east. The Spanish possessions are known as Rio de Oro. In the south the French influence extends beyond the Sahara, reaching the coast in Senegal, French Guinea, Ivory coast, Togo and Dahomey. The French Sahara proper may be very roughly estimated at about 1,500,000 sq. miles. Over the whole of French West Africa there is a governor-general, who is assisted by a council. The seat of the General Government is at Dakar. Under the governor general the various colonies are administered by lieutenant-gov ernors.
Exploration.—The Egyptians penetrated the Libyan and Nubian deserts at points, and Carthaginians and Phoenicians were acquainted with the northern fringe of the desert in the west. Jews and Genoese in the middle ages learned much about the Sahara in the course of trade, and their knowledge was mapped by Jewish cartographers in Majorca in the 14th and 15th cen turies. In 1819 Capt. G. F. Lyon and Joseph Ritchie penetrated from Tripoli to Murzuk. In 1822 came the journey of Oudney, Clapperton and Denham, from Tripoli to Lake Chad, and a year or two later Maj. A. G. Laing reached Timbuktu, also from Trip oli. In 1828 Rene Caillie crossed from Timbuktu to Morocco. Heinrich Barth, in the course of his great journey (1849-1856), commenced from Tripoli under the leadership of James Richard son, traversed a considerable portion of the Sahara. Between 1859 and 1861 Henri Duveyrier explored parts of the Tuareg do main. Knowledge of the northern Sahara, from Morocco to Trip oli, was largely increased by the journeys of Gerhard Rohlfs, begun in 1861; Rohlfs subsequently crossing (1865) from Tripoli to Lake Chad by nearly the same route as that previously taken by Barth. In 1873-74 Rohlfs visited the oases in the north of the Libyan desert, and in 1878-79 reached the oasis of Kufara. In 1876-77 Erwin von Bary, made his way to Ghat and Air. A French expedition under Col. Paul Flatters, after penetrating far south of Algeria, was massacred (1881) by Tuareg. Farther west, in 188o, Dr. Oskar Lenz started from Morocco, partly by a new route, to Timbuktu. In 1892 the Sahara was crossed from Lake Chad to Tripoli by the French Colonel Monteil.