Serengeti National Park is undoubtedly the best-known wildlife sanctuary in the world, unequalled for its natural beauty and scientific value, it has the greatest concentration of plains game in Africa.It is the migration for which Serengeti is perhaps most famous. Over a million wildebeest and about 200,000 zebras flow south from the northern hills to the southern plains for the short rains every October and November, and then swirl west and north after the long rains in April, May and June. So strong is the ancient instinct to move that no drought, gorge or crocodile infested river can hold them back.