Unfortunately, the modern history of Africa is rife with many such tribal movements. Just to give you one example, the 1994 genocide in Rwanda triggered a tribal migration of first the Tutsis and then the Hutus as each fled the other and the slaughter that was occurring. You might also like to think about the migration of the population of Zimbabwe to countries like South Africa as they flee the despotism of Robert Mugabe.
One of the great migrations that took place in Africa is that of the Bantu. The Bantu comprise a language group. Many of those who speak variations of the Bantu language have differing ethnicities and cultures, but are connected by language. The Bantu originated in west-central Africa around the modern day countries of Nigeria and Cameroon. This migration began around 1000 B.C. Previous to this time, the Bantu people learned how to use iron and developed iron tools which aided them in farming. These iron tools allowed for an increase in food production which in turn led to an increase in population. In time, there came to be a shortage of arable land for the increased population and people were forced to move. This migration was a slow process and took place over a long period of time—1500 years. The Bantu first began to move into central Africa. As they settled, their populations continued to grow and a second wave of migration took place as the Bantu continued to move east and south until they reached the southern tip of Africa. This gradual migration was mostly peaceful. The people with whom the Bantu came into contact intermarried with the Bantu and exchanged ideas. These interactions eventually led to a blending of cultures. The end result of this migration was that the Bantu-speaking peoples became the dominant group in Sub-Saharan Africa. An interactive map showing this migration can be found at Bantu Migration Map.
The peoples in the African nations of Rwanda, Somalia, Sudan, Zimbabwe, and the Congo have seen great numbers of people being displaced from those countries. A full accounting will never be accurately described from all the tensions that have developed over the years.