How did African culture change once it make contact with the outside world?
There are may ways in which to answer this question. Whenever two cultures meet there is a process of syncretism. Both societies change in the cultural interchange. In light of this, let me give a few examples.
First, Africa changed on a religious level. Much of Africa is now filled with Christians and Muslims. The traditional religions of Africa are now on the decline. The impact of religion is great, because it shapes the worldview of people and eventually the nation. A person who has work on this area is Philip Jenkins, professor at Pennsylvania State University.
Second, Africa has changed in terms of language. Through colonization, many African countries speak English and French. This too is no small change.
Third, Africa has become more Western in its technology, goals, and worldview.