especially diamond, gold, bauxite and aluminium. The country is a member of the United Nations, African Union, Economic Community of West African States (ECOWAS), Mano River Union, Commonwealth of Nations, IMF, World Bank, WTO, African Development Bank, and Organisation of Islamic Cooperation. Sierra Leone is home to Sub-Saharan Africa's first Western-style university: Fourah Bay College (established in 1827). Etymology The country takes its name from the Lion Mountains near Freetown. Originally named (Portuguese for 'lioness mountains') by Portuguese explorer Pedro de Sintra in 1462, the modern name is derived from the Venetian spelling, which was introduced by Venetian explorer Alvise Cadamosto and subsequently copied by other European mapmakers. History Early history Archaeological finds show that Sierra Leone has been inhabited continuously for at least 2,500 years; populated successively by societies who migrated from other parts of Africa. The use of iron was adopted by the ninth century, and by 1000 AD, agriculture was being practised along the coast. Over time, the climate changed considerably, altering boundaries between different ecological zones, affecting migration and conquest. Sierra Leone's dense tropical rainforest and swampy environment were considered impenetrable; it was also host to the tsetse fly, which carried a disease fatal to horses and the zebu cattle used by the Mande-speaking people. This environment protected its people from conquest by the Mandinka and other African empires, and limited the influence of the Mali Empire. Islam was introduced by Susu traders, merchants and migrants from the north and east, becoming widely adopted in the 18th century. European trading European contacts within Sierra Leone were among the first in West Africa during the 15th century. In 1462, Portuguese explorer Pedro de Sintra mapped the hills surrounding what is now Freetown Harbour, naming the shaped formation Serra da Leoa or "Serra Leoa" (Portuguese for Lioness Mountains). The Spanish rendering of this geographic formation is Sierra Leona, which later was adapted, misspelled and became the country's current name. Though according to Professor C. Magbaily Fyle, this might have been a misinterpretation from historians. According to Professor Fyle, there has been evidence of travellers calling the region Serra Lyoa long before 1462 (before the first arrival of Sintra to the region). This would imply that the identity of the person who named Sierra Leone is unknown. Soon after Sintra's expedition, Portuguese traders started arriving at the harbour. By 1495 they had built a fortified trading post on the