The UN is supporting about 11 million refugees in Burundi, Central African Republic, Chad, Congo (Brazzaville), Congo, Ethiopia, Kenya, Somalia, Sudan and Uganda. Congo, Somalia and Sudan are the worst cases, with ethnic conflict and civil war being the main cause. Most (83 percent) of these refugees are still in their native country, but driven from their homes by the fighting. The rest have fled to a neighboring country. Most of the costs of the food and medical aid, and peacekeeping, are paid for by Western nations, with the U.S. being the largest contributor. Over 30,000 peacekeepers are deployed in these countries, but that's not enough troops to halt the violence, or protect the refugees.
This region has always been violent. During the colonial period (mid 19th to mid 20th century), there was much less fighting, because colonial troops kept the peace by force. This was expensive, and that cost was one of the reasons why the colonial powers departed after World War II. Locally raised armies, often containing troops trained by the departed colonial powers, kept things quiet for a while. But by the end of the 20th century, those forces had fallen apart due to corruption and poor leadership. Chaos has ensued, and no one has yet come up with a quick, clean and cheap solution.