It is clear from the few archaeological findings on Sierra Leone that people lived in the present area of Sierra Leone a very long time ago. Examinations of tools discovered in a cave in Yengema suggested that people inhabited that area at least 2,500 years before Christ. These people lived in small communities. We do not know for certain who they were. By the time Portuguese traders began to appear on the West African Coast in the mid-fifteenth century, certain groups had already established themselves firmly in many areas in what is now Sierra Leone. On the coast were a host of communities such as the Baga, Bullum, Krim and Vai. The Portuguese called these coastal peoples the Sapes. In the North lived the Limbas. The Banta were found in the south-west while the Kissi and Kono lived in the East. Each group tended to be isolated from the others and there was very little internal migration. This was due to fear of war, suspicion of people from other groups, problems of social cohesion within the group and possible breakdown of traditions. These were all factors affecting ethnic diffusion.
The early peoples of Sierra Leone seem to have been affected by certain invasions, such as those of the Mane. Some groups were absorbed in the process, and others were displaced, while new groups were formed subsequently. Over a long period of time, new communities also came in a rather peaceful manner and settled in various parts of the country. Like the early inhabitants, these later immigrants also first lived separate from each others, but the growth of trade, provision of western educational and medical facilities, improvement in transportation systems, mining, agriculture and migration tended to draw the groups closer together.
Today, there are at least 17 ethnic groups in the country. These groups have been divided into three language categories - Mande, Mel and Others. The Mende, Vai/ Gallinas, Kono, Loko, Koranko, Soso, Yalunka and Mandingo belong to the Mande. The Temne, Bullum/ Sherbro, Kissi, Gola, and Krim form part of the Mel group. The Others are Limba, Fula, Krio and Kru. The two largest communities are the Mende and Temne, each accounting for about 31 percent of the population.
The Mende, who are believed to be descendants of the Mane, were originally in the Liberian hinterland. They began moving into Sierra Leone slowly and peacefully in the eighteenth century. The Temne claim to have come from Futa Jallon, which is in present-day Guinea. The Limba are the third largest and one of the oldest communities in Sierra Leone. They have no tradition of origin and maintain that they have always lived in Sierra Leone. It is believed that their settlement was around the Wara Wara hills in the northern interior. The Vai and the Kono are related people who split up some time ago. Oral tradition states that there was shortage of salt in Konosu, the original home of the Vai and the Kono, which is somewhere in present-day Guinea. The people therefore decided to set out en masse in search of salt water. After travelling for many months, some of them got tired and decided to settle in approximately the present Kono homeland. The Loko are akin to the Gbandi of Liberia and the Mende. It is believed that the Loko were offshoots of a Mane expeditionary force sent against one of the defected Mane viceroys in the 1550s. The Koranko are related to the Mandingo. They are believed to have began arriving in Sierra Leone from Guinea in about 1600. The Soso and the Yalunka are a branch of the same people. Soso and Yalunka tradition maintains that they arrived in Futa Jallon some time after the Temne and Baga had created a powerful state to the east of Futa. As a result of the increase in population, the Soso began to spread out into north-western Sierra Leone in about the seventeenth Century. The Bullum are among the oldest inhabitants on the Sierra Leone coast. They were invaded by the Mane warriors in the Sixteenth century who in the process "cut the Bullum tribe into two parts". The northern branch were assimilated by the Temne and the Soso. The Southern branch came to be known as Sherbro, a name which was derived from Sherabola, a Mane viceroy who imposed his rule on them towards the end of the Sixteenth century. The Krim are a coastal people akin to the Sherbro and live to the south- east of the Sherbro. The Gola, the majority of whom live in the Liberian hinterland, are also among the earliest inhabitants of Sierra Leone. They occupy some land east of the Gallinas on the present-day Guinea. The Kissi say they migrated from upper Niger before the fifteenth cenutry. They were attacked by the Koranko who pushed them towards the eastern border with present-day Guinea. The Mandingo and the Fula began arriving in Sierra Leone in the seventeenth century. The first immigrants were mostly traders and Islamic teachers. the Mandingo came mainly from the Sankaran region in Guinea while the Fula came from Futa Jallon and Senegal. They subsequently settled in various parts of the country. The Krio community, who largely inhabit the Western Area, came into being in the mid-nineteenth century as a result of the integration of such disparate groups as the Original Settlers, Nova Scotians, Maroons, Recaptives and immigrants from the Sierra Leone hinterland. The Kru began arriving in the Sierra Leone colony from Liberia in the 1790s. They were mostly seamen. As their numbers increased, land was acquired for them near the shore beyond Sanders Brook in the west end of Freetown.