This is a braided sling. Braiding is not a hard thing to do once you know how. These slings usually have a decent life and are very strong. I made this sling from sisal to give it an old look, but you could also make it from modern twine. If you leave some strands at the end of the release cord, it will give a nice snap. You could also stitch some leather on the pouch to get a closed pouch. The length of this sling folded is about 65cm, a rather short sling, good for short range.
Instructions for making a braided sling can be found here - http://slinging.org/index.php?page=making-a-braided-sling-an-illustrated-guide