<P> The Kingdom of Nri was a West African medieval state in the present - day southeastern Nigeria and a subgroup of the Igbo people . The Kingdom of Nri was unusual in the history of world government in that its leader exercised no military power over his subjects . The kingdom existed as a sphere of religious and political influence over a third of Igboland and was administered by a priest - king called as an Eze Nri . The Eze Nri managed trade and diplomacy on behalf of the Nri people and possessed divine authority in religious matters . </P> <P> The Oyo Empire was a Yoruba empire of what is today Western and North central Nigeria, . Established in the 15th century, the Oyo Empire grew to become one of the largest West African states . It rose through the outstanding organizational skills of the Yoruba, wealth gained from trade and its powerful cavalry . The Oyo Empire was the most politically important state in the region from the mid-17th to the late 18th century, holding sway not only over most of the other kingdoms in Yorubaland, but also over nearby African states, notably the Fon Kingdom of Dahomey in the modern Republic of Benin to the west . </P> <P> The Benin Empire was a pre-colonial empire located in what is now southern Nigeria . Its capital was Edo, now known as Benin City, Edo . It should not be confused with the modern - day country called Benin, formerly called Dahomey . The Benin Empire was "one of the oldest and most highly developed states in the coastal hinterland of West Africa, dating perhaps to the eleventh century CE", . The Benin Empire was governed by a sovereign Emperor with hundreds of thousands of soldiers and a powerful council rich in resources, wealth, ancient science and technology with cities described as beautiful and large as Haarlem . "Olfert Dapper, a Dutch writer, describing Benin in his book Description of Africa (1668) ". Its craft was the most adored and treasured bronze casting in the history of Africa . It was annexed by the British Empire in 1897 during the invasion and scramble of Africa . </P> <P> Portuguese traders began establishing settlements along the coast in 1445, followed by the French, British, Spanish, Danish and Dutch; the African slave trade began not long after, which over the following centuries would debilitate the region's economy and population . The slave trade also encouraged the formation of states such as the Asante Empire, Bambara Empire and Dahomey, whose economic activities include but not limited to exchanging slaves for European firearms . </P>

Map of west africa showing countries and capitals