The effect that the African slave trade had on American society and the slaves themselves has been long documented. What is often overlooked is the effect that the slave trade had on Africa itself. How did the slave trade effect native Africans and their governments?
Before the Europeans showed up and began exporting slaves, Africa was largely made up of many small tribes who often warred with each other. No one tribe could become too big because it might have many enemies, several of which might gang up on the powerful tribe if it threatened to become too powerful. There were a few exceptions in which tribes built powerful trading empires, but these were usually far inland near the center of African trade and their influence was restricted mainly to commercial interests.
That changed with the Europeans showed up, however. Suddenly, the center of trade in Africa moved to the Western coast of the continent were Europeans traded with the villages along the coast. Being in the new center of trade in Africa, these villages became the most important in Africa. Those coastal tribes which were the most skilled at capturing slaves soon became the most powerful tribes on the continent.
Tribes that had access to revenue from the slave trade now had an advantage over their neighbors who did not. With this revenue, they could purchase European weapons and other tools of conquest. As they gained power over their neighbors, they kidnapped members of those tribes to sell as slaves and incorporated those tribes into ever growing empires. This process was fueled by slavery and required that the new empires obtain a steady supply of slaves in order to maximize their revenues. The more slaves these empires could kidnap and sell to Europe, the bigger their profits and the more their influence grew. With greater influence, came greater opportunity to kidnap neighbors as slaves. Therefore, the whole process fueled itself so long as the Europeans continued to buy slaves.
Thus, these empires relied heavily on slavery, which made them dependent on trade with Europeans for their power. If the Europeans stopped trading with a particular tribe or if they had outlawed the slave trade earlier than the 19th century, these empires could not have sustained themselves. By the time the Europeans stopped participating in the slave trade, these empires were largely established. Many of them collapsed without the steady income that slavery had afforded them. Others remained more or less intact until the British returned to set up colonies in Africa.
