European exploration of Africa 1840s, so that around the midpoint of the 19th century and the beginning of the colonial Scramble for Africa, the unexplored parts were now limited to what would turn out to be the Congo Basin and the African Great Lakes. This "Heart of Africa" remained one of the last remaining "blank spots" on world maps of the later 19th century (alongside the Arctic, Antarctic and the interior of the Amazon basin). It was left for 19th-century European explorers, including those searching for the famed sources of the Nile, notably John Hanning Speke, Sir Richard Burton, David Livingstone and Henry Morton
History of slavery in the Muslim world up until the 19th century. Livingstone and Stanley were then the first Europeans to penetrate to the interior of the Congo basin and to discover the scale of slavery there. The Arab Tippu Tib extended his influence and made many people slaves. After Europeans had settled in the Gulf of Guinea, the trans-Saharan slave trade became less important. In Zanzibar, slavery was abolished late, in 1897, under Sultan Hamoud bin Mohammed. The rest of Africa had no direct contact with Muslim slave-traders. While slaves were sometimes employed for manual labour during the Arab slave trade, this was usually the exception