Image by Edgley Cesar via Flickr
In Swahili, time is represented by the rise of the sun which, being almost on top of the equator, is usually at 6 AM. So. Being pastoralists 3:00 is 9:00 because it is 6hours past the sunrise. Reverse for the afternoon - so 7:00 is 1:00 PM.
Thus endeth the lesson.