What is the Great Animal migration of Africa?

There are many animals that migrate in Africa, and quite a few can be described as great, for instance: there used to be a large springbok migration in southern Botswana and the north-western South Africa. But the most famous one is on the Serengeti plains (from the Serengeti National Park in Tanzania to the Masai Mara reserves in upper Kenya). These wildebeest and zebras forms the largest and longest overland migration in the world.