Senegambia, a region of western Africa, formerly comprising only the territory lying between the rivers Senegal and Gambia, from which it derives its name, but now held to include the whole of the country between the former river and the British colony of Sierra Leone. It is bounded N. by the Sahara, E. by Soodan, S. by Sierra Leone, and W. by the Atlantic, and extends from lat. 9° to 17° N., and from about Ion. 10° W. to Cape Verd, in Ion. 17° 34' W. Its eastern boundary is so indefinite that an accurate estimate of the area is impossible; it can hardly be less than 200,000 sq. m., and has been placed much higher. The population is estimated at 9,000,000. It includes the French colony of Senegal, and French power predominates on the coast and in the country. There are English settlements along the Gambia, of which Bathurst at its mouth is the principal town and the seat of government; and the Portuguese establishments at the mouth of the Rio Grande and in the interior in 1873 embraced a territory of 43 sq. m., with 8,500 inhabitants. The objects of these foreign establishments are purely commercial.

The coast region of Senegambia consists of a belt of level land extending inland from 150 to 200 m., which in the north is for the most part open, sandy, low, and barren, with here and there a few rocky cliffs; but S. of the Gambia the aspect of the country changes, the vegetation becomes luxuriant, and the deeply and frequently indented coast is bordered by mangrove swamps, back of which rises a rich forest region. The principal rivers, described under their own titles, are the Senegal and Gambia, S. of which three others of considerable size empty into the Atlantic: the Casamanza or Casemanche, navigable 80 m. from its mouth; the Rio Grande, 400 m. long; and the Nuńez, of about half that length. With the exception of the coast and the alluvial flats along the rivers, the country is undulating, and rises in terraces from the ocean to the mountains of the interior, which overspread the S. E. portion, and attain an elevation variously stated at from 3,000 to 6,000 ft. Little is known of Senegambian geology, except the occurrence of granite in the mountainous region. Iron ore is abundant in the elevated districts, and gold is found in large grains lower down. The climate is reputed to be the most continuously hot of any in the world.

The highest temperature is experienced in the vicinity of the Sahara, in the north, where the mercury sometimes rises to 110° F. in the shade; on the coast the average is about 80°. Throughout most of the country the rainy season lasts from June to December inclusive, and is characterized by tornadoes at midsummer, with thunder and lightning of tropical intensity. Much of the land is exceedingly fertile. In the forests are found the oil-producing palm and many valuable kinds of timber, gums, and caoutchouc; cardamoms, ground nuts, and cassia are also obtained, and indigo grows wild. Wild coffee also is abundant on the banks of the Nuńez. Rice, maize, and millet are the chief grains cultivated. Hemp is extensively grown. All the domestic animals of Europe are found, in addition to which there are camels in the desert country of the Jaloofs. Large numbers of cattle are raised on the pasture lands of the terraces. Elephants are very numerous, and the hippopotamus is found in all the rivers. Buffalo, deer, a species of eland, antelopes, wild boars, hares, porcupines, lions, panthers, and hyaenas are all natives of the country.

Crocodiles are numerous, and the boa frequents the marshy grounds. - The inhabitants consist of the aboriginal negro tribes, Moors, and the offspring of these two races, a people of middle size, of a light copper color, well made and active. Many of the women are remarkably handsome, and both sexes dress neatly. They are much more civilized than the black tribes, of which the lower type is found along the coast, while the Mandingoes, the Jaloofs, and others of this mixed descent dwell further inland, and live under regular governments, generally consisting of a king and hereditary nobility. They keep large numbers of slaves. The Mohammedan religion prevails among them. There are about 20 native states in the country. The most important of these is the Foolah state of Foota Jallon, with its capital at Timbo, occupying an elevated plateau over 80 m. square, in the south, near the head waters of the Senegal. (See Foota Jal-lon.) The kingdom of Bondoo and the territory of Foota are described under their own titles, as is also the Mandingo country proper, which some include in Senegambia. Besides the trade carried on by the French, English, and Portuguese from their settlements upon the three rivers, which is mainly in palm oil, gum, hides, beeswax, ground nuts, and wild coffee, a considerable traffic exists between Senegambia and the countries lying further E. Much of the gold found in the elevated districts is carried to Timbuctoo, and thence finds its way to the countries N. of the Sahara. - The Carthaginians visited this part of the coast of Africa, and the Portuguese reached it between 1444 and 1469. The latter nation formed several commercial establishments, but afterward neglected them when they discovered the route to India. The British acquired their possessions on the Gambia in 1631, and the French settled on the Senegal in 1637.