Here are some images of steatopygia. One name for it is the Hottentot bustle.
What man in OP's image has looks a little different, the more I look at it. In Khoisan, the thighs are not that large, and it goes back so horizontally it's like a shelf. What OP's image has is closer to what you see in a small number of black women where both the ass and thighs are extremely exaggerated, both in back and to the sides. Also including a couple of images of that.
I've seen white women with this as well, but it's much rarer.