The impact of trans-Atlantic slave trade on African societies can be viewed from many angles. Some Africa rulers used the weapons they acquired from the sale of slaves to expand their polities by raiding other kingdoms. This led to empire building. The most important impact of the slave trade on Africa was the reduction of its population. For example, it has been estimated by historians that during the whole period of the slave trade, about 25 million people, at least, were sent out of Africa south of the Sahara. Majority of these people were captured through wars, raids and kidnapping. This means many more people over and above the number exported must have been killed or disabled in the process of violent acquisition. Although some of the wars were fought for reasons independent of the trade, many wars were also, directly or indirectly, connected with the slave trade.
The economic motivation by states looking for more revenue through selling slaves, the fear of their neighbours, and the increasing availability of firearms and horses associated with the external slave trade had established more frequent warfare and violence in many African societies. Deaths associated directly or indirectly to the slave trade system were part of the impact. As a result of an increasing atmosphere of insecurity, inter-regional trade among African states and economic integration were retarded. The absence of peace and stable economy made population growth almost impossible in many societies. Similarly, the continuous wars led to famine, and weakened resistance to diseases.
The relative ages of those sold into slavery were between 16 and 45. As such, even if the total number of slaves was very small compared with the total population of their communities, still, being the most active part of society made growth of the affected communities very difficult. Younger people sold into slavery would have been the ones to be on the farms; their absence decreased market activities and made economic development almost impossible.