Years ago, after sent on a vacation to recover from an infection, I stayed in eastern Zimbabwe (which was Rhodesia back then).
We hiked the mountains behind the mission, and it was terraced with stones about 1 to 2 feet high and flat for 2 to 3 feet, if I remember correctly.
But although these were ancient terraces, I could never find the history of who made them or why.
Right now, on Scribd, I am reading Brian Fagan's book Elixir, about water, and he notes that these were irrigation type farming found in several areas of East Africa...most of what he describes is furthur north but he also mentions these and that the Drackenburg mountains have some.
the Wikipedia article only notes those of the Great Lake Region. more HERE.which is about the SA and Zim terraces.
I'll have to read it more carefullywhen I'm more alert. One problem of reading on line is that it's hard to go back and forth and take notes.