Sierra Leone occupies 71,740 square kilometers on the Atlantic coast of West Africa between Guinea to the north and Liberia to the southeast. The country divides administratively into four provinces plus the Western Area containing Freetown. The terrain rises from coastal swamps and the Sierra Leone River estuary through interior plains to mountains along the northeastern border. The Loma Mountains contain Bintumani peak at 1,948 meters, the highest point in West Africa west of Mount Cameroon. The Rokel River runs 250 kilometers from interior highlands to the Atlantic near Freetown. The Moa River forms much of the southeastern border with Liberia while the Jong River drains western interior regions. The climate follows two seasons: rains from May through November and dry harmattan winds from December through April. Freetown receives approximately 3,000 millimeters of annual rainfall, among the wettest capitals globally.
The population reached approximately 8.4 million in 2021 census estimates. No single ethnic group commands a majority. The Mende concentrate in the south and east, the Temne in the north and west. The Limba inhabit northern interior districts. The Kono live in eastern diamond-mining regions around the city of Koidu. Smaller populations include the Kuranko near the Guinea border, the Susu in northern coastal areas, the Loko in central-north districts, the Sherbro on southern coastal islands, the Fula as mobile pastoral groups, the Mandingo as trading communities, the Kissi in eastern border regions, and the Vai near the Liberian frontier. The Krio represent approximately two percent of the population but exert cultural influence beyond numbers. This group descends from liberated Africans landed in Freetown after British naval interception of slave ships in the nineteenth century, along with earlier settlers from Nova Scotia, Jamaica, and directly from British abolitionist initiatives.
English serves as the official language for government and formal education. Krio functions as the lingua franca understood by an estimated ninety-five percent of the population. Krio developed from English vocabulary with syntax influenced by Yoruba and other West African languages during the settlement period after 1792. Mende speakers number approximately two million, concentrated in the Southern and Eastern provinces. Temne speakers number approximately 1.8 million in the Northern and Western provinces. Limba speakers total approximately 600,000 in northern interior districts. Other languages include Kono spoken by approximately 300,000 people, Kuranko by 200,000, Susu by 150,000, Loko by 140,000, Kissi by 120,000, Vai by 25,000, and Fula by pastoral groups. These figures represent first-language speakers; multilingualism remains common with individuals typically speaking their ethnic language, Krio, and often English.
Sierra Leone existed as fragmented chiefdoms and small kingdoms before European contact. The Mende established agricultural settlements in southern forest zones by the sixteenth century. The Temne controlled northern territories and coastal access. The Portuguese navigator Pedro de Sintra reached the coast in 1462 and named the mountainous peninsula Serra Leoa, lion mountains, possibly describing the shape or the sound of thunder echoing from peaks. The British established a trading post on Bunce Island in the Sierra Leone River estuary in 1670. This fort exported rice, ivory, and enslaved people to British American colonies, particularly South Carolina where Bunce Island captives provided rice-cultivation knowledge. Between 1670 and 1807 approximately 30,000 enslaved Africans passed through Bunce Island.
The Province of Freedom was founded in 1787 when the Committee for the Relief of the Black Poor transported approximately 400 formerly enslaved people and British women to land purchased from Temne chief King Tom near the present site of Freetown. This settlement collapsed within two years from disease, hostile relations with neighboring communities, and internal disorder. In 1792 the Sierra Leone Company established Freetown as a permanent settlement for 1,196 people who had fled American slavery to British lines during the Revolutionary War, received freedom in Nova Scotia, then relocated to Africa. Lieutenant John Clarkson, brother of abolitionist Thomas Clarkson, led this migration aboard fifteen ships. The settlers laid out Freetown in a grid pattern on March 11, 1792. The settlement received approximately 550 Maroons deported from Jamaica in 1800 after their rebellion against British colonial authorities.