There is an African plain, there are trees, grasses, some seasonal rivers/lakes, and snakes.
Upon the plain lives a society of tribesmen (think along the lines of the Maasai Mara people)
These tribes love life, but hate snakes - they are the embodiment of the evil spirits, they cannot be eaten, they also cannot be killed (life is more treasured than evil is hated).
Of course, there's plenty of snakes around.
So the question (obviously) is how can the tribesmen get the snakes off the plain?