Rumours of the existence of the Bahr-el-Ghazal led some of the Greek geographers to imagine that the source of the Nile was westward in the direction of Lake Chad. The first map on which the course of the Ghazal is indicated with anything like accuracy is that of the French cartographer d'Anville, published in 1772. The exploration of the river followed the ascent of the White Nile by the Egyptian expeditions of 1839-1842. For a considerable portion of the period between 1833 and 1865 John Petherick, a Welshman, originally a mining engineer, explored the Ghazal region, particularly the main stream and the Jur. In 1859 a Venetian, Giovanni Miani, penetrated the southern regions of the Ghazal basin and was the first to bring back reports of a great river (the Welle) flowing west beyond the Nile watershed. In 1862 a Frenchman named Lejean surveyed the main river, of which he published a map. In 1863 Miss Alexandrine Tinné (q.v.) with a large party of friends and scientists ascended the Ghazal with the intention of seeing how far west the basin of the Nile extended.
The chief scientists of the party were the Germans, Theodor von Heuglin and Hermann Steudner. Considerable additions to the knowledge of the region were made by this expedition, five out of the nine white members of which died from blackwater fever. Georg Schweinfurth (q.v.) between 1869 and 1871 traversed the whole of the southern district, and crossing the watershed discovered the Welle. The efforts to destroy the slave trade in the Ghazal province led (1879-1881) to the further exploration of the river and its tributaries by Gessi Pasha, the Italian governor under General C. G. Gordon. Wilhelm Junker (q.v.) about the same period also explored the southern tributaries of the Ghazal. These were carefully surveyed, and the Jur (Sue) followed throughout its course by Lieutenant A. H. Dyé and other members of the French mission under Colonel (then Captain) J. B. Marchand, which crossing from the Congo (Oct. 1897) reached Fashoda on the White Nile in July 1898.
Like the Bahr-el-Jebel the Bahr-el-Ghazal is liable to be choked by sudd. Gessi Pasha was imprisoned in it for some six weeks. The river became almost blocked by the accumulation of this obstruction during the rule of the Mahdists. In 1901 and following years the sudd was removed by British officers from the Bahr-el-Ghazal, the Jur and other rivers. Uninterrupted steamboat communication was thus established during the flood season between Khartum and Wau, a distance of some 930 m. In 1905-1907 R. C. Bayldon, a British naval officer, Capt. C. Percival and Lieut. D. Comyn partly explored the northern and western affluents of the Ghazal, and threw some light on the puzzling hydrography and nomenclature of those tributaries.
See Nile and the authorities there quoted, especially Sir William Garstin's Report upon the Basin of the Upper Nile, Egypt, No. 2 (1904), and Capt. H. G. Lyons's The Physiography of the River Nile and its Basin (Cairo, 1906); also The Geographical Journal, vol. xxx. (1907).
(W. E. G.; F. R. C.)
 The Lol is also called the Kir, a name given likewise to the lower course of the Bahr-el-Homr. The confusion of names is partly attributable to the fact that each tribe has a different name for the same stream. It is also due in part to the belief that there was a large river flowing between the Bahr-el-Homr and the Lol. This third river, generally called the Kir, has proved to be only the lower course of the Lol of Bahr-el-Arab.
 Including Miss Tinné's mother and aunt and Dr Steudner.