This part of the Guinea coast was made known by the Portuguese voyagers of the 15th century. In consequence, largely, of the dangers attending its navigation, it was not visited by the European traders of the 16th-18th centuries so frequently as other regions north and east, but in the Rio Pongo, at Matakong (a diminutive island near the mouth of the Forekaria), and elsewhere, ''slave traders'' established themselves, and ruins of the strongholds they built and defended with cannon, still exist ''(e.g., Fortin de Boké)''. When driven from other parts of Guinea the slavers made this difficult and little known coast one of their last resorts, and many ''barracoons'' were built in the late years of the 18th century. It was not until after the restoration of Goree to her at the close of the Napoleonic wars that France evinced any marked interest in the region. At that time the British, from their bases at the Gambia and Sierra Leone, were devoting considerable attention to these
Rivières du Sud (''i.e,'' south of Senegal) and also to the Futa Jallon. René Caillié, who started his journey to Timbuktu in 1827, did much to quicken French interest in the district, and from 1838 onward French naval officers, Bouèt-Willaumez and his successors, made detailed studies of the coast.〔(''The Encyclopædia Britannica'' ), 1910, p. 103〕