In studying Asian archery, Manchu mostly, I've read that the fletching was very long, 6-8", but very narrow. Now since most Asian archery from this region whether shot from the ground or not stems from horse archery the theory goes that the somewhat shorter ranges involved in horse archery combined with the moving perpendicular to the target led to this fletching design. But again, with any Asian martial art everything must be taken with a grain of salt due to the mysticism the west seems determined to attribute to it, lol.