In Japan, sumo wrestling was under Imperial patronage between 710 and 1185 and was a popular spectator sport. During this era it was refined from a brutal submission spectacle into a highly ritualized toppling match in which victory could be gained by forcing the opponent out of a 15-foot circle. Then, under the shoguns, public matches were banned, and martial forms of the sport for the samurai, or military caste, were emphasized instead. Professional sumo wrestling in Japan dates from the revival of public matches after 1600 and is often called the Japanese national sport. Six great championships are held annually, attracting immense crowds, and several hundred athletes make their living at this sport. A complex system of ranking leads to the designation of Yokozuna, or “grand champion.” The list of men awarded this title commences with Akashi Shiganosuke, victor in 1632. Specially selected youths are brought up into the profession and fed a special protein diet, which creates immense, bulky bodies. Exceptionally agile men weighing 300 pounds or more are common in this sport. Lengthy rituals and elaborate posturings accompany the bouts, which are, by contrast, quite brief, often lasting only a few seconds.