Introduction to the African Region: Africa not only has rivers such as the Nile River and the Congo River, but also the East African Great Rift Valley Lake Area, which contains many kinds of fish. The most eye-catching ones are Lake Victoria, Lake Tanganyika and Mara. Cichlids from Lake Wei. These lakes were formed between 500,000 and 2 million years ago. At that time, a small number of fish entered the lakes from rivers and each adapted to their new environment. After numerous differentiations, they evolved into today's prosperous society.