Medieval technology and social continuity
Histories of technology (*cough*) tend to treat the breast-strap horse harness as something that was rendered obsolete by the padded collar and disappeared by the year 1200 AD. However, it turns out it's alive and well in Romania and it has certain advantages over the padded collar. Transylvanian Horseman has an interesting photo-filled post on the relative merits of both harnessing systems over at his blog.