Maybe totally unrelated walls but we have a few rock walls on my family property. One keeps the cows off the road others just divide old property lines. Story is a man and his two “simple” sons were in the area years ago building them. Nobody really knows more than that. Considering people in their 80’s and 90’s don’t really know I’d say maybe 1920’s on the new end and couldn’t be before 1860’s when the area was open to settlement. About a similar height and construction. Hopefully that helps some, like I said could be a totally different story with yours.