My house was built in 1920 and has a basement with a "shelf wall?" that starts in the middle of the south wall and goes east all the way around to the middle of the north wall (half of the basement). It's a 3 foot by 3 foot ledge or shelf on the floor against the wall. Is this called a "shelf wall" or "ledge wall" or am I even close?

When I was house hunting, I came across several different variances of this type of basement wall. I saw only one wall done, 2 adjacent walls done, all 4 walls and then like mine.

What was the reason for this type of construction in a basement? To me it seems like a total waste of valuable space. Anyone have any info on this?

Thanks in advance!