Martial arts similar to sumo have been performed around the world since long ago. In Japan, figurines of sumo wrestlers have been unearthed dating back to between the third and seventh centuries. Sumo reportedly began as a ritual in Shinto ceremonies to entertain the gods. In the Nara period (710-794) and Heian period (794-1192), sumo became an event conducted at the imperial court, and bouts were performed in front of the emperor. Early sumo was a rough and tumble affair that combined elements of boxing and wrestling and had few laws. Under the patronage of the Imperial Court rules were formulated and techniques were developed. In the Kamakura Period (1185-1333) sumo was used to train samurai and to settle disputes.
Sumo wrestling has been a profitable, professional sport for four centuries. In the Edo period (1603-1867) sumo tournaments were often held in Tokyo, Osaka and Kyoto. The basic organization and rules of sumo have changed little since the 1680s. Up through the early 20th century, there were only two basho a year, however, as sumo's popularity grew, the number of major tournaments increased to current six basho a year in 1958. Sumo's popularity was further enhanced by the late Emperor Showa. Beginning with the 1955 tournament, the emperor made a custom of attending one day of each tournament held in Tokyo. Sumo is also an amateur sport. International Sumo Federation (IFS) was formed in 1992.
In 1907 Yokozuna Hitachiyama visited America and began the introduction of Sumo to foreign countries, while sumo was first practiced outside of Japan by members of the overseas Japanese community and several decades ago the sport began to attract other nationalities. Since the 1960s, young wrestlers from the United States, Canada, China, South Korea, Mongolia, Argentina, Brazil, Tonga, Russia, Georgia, Bulgaria, Estonia, and elsewhere have come to Japan to take up the sport, and a few of them have excelled. Thanks in part to greater dissemination of sumo overseas by exhibition tournaments the sport is gaining popularity outside Japan. Professional sumo is organized by the Japan Sumo Association.