Information found from  http://sumo.goo.ne.jp/eng/ozumo_joho_kyoku/shiru/kiso_chishiki/beginners_guide/origin.html   A ccording to Japanese legend the very origin of the Japanese race depended on the outcome of a sumo match. The supremacy of the Japanese people on the islands of Japan was supposedly established when the god, Take-mikazuchi, won a sumo bout with the leader of a rival tribe. Apart from legend, however, sumo is an ancient sport dating back some 1500 years.

I ts origins were religious. The first sumo matches were a form of ritual dedicated to the gods with prayers for a bountiful harvest and were performed together with sacred dancing and dramas within the precincts of the shrines.

The Nara Period（The 8th century）sumo was introduced into the ceremonies of the Imperial Court. A wrestling festival was held annually which included music and dancing in which the victorious wrestlers participated. Early sumo was a rough-and-tumble affair combining elements of boxing and wrestling with few or no holds barred. But under the continued patronage of the Imperial Court rules were formulated and techniques developed so that it came more nearly to resemble the sumo of today.

A military dictatorship was established in Kamakura in 1192 and a long period of intense warfare ensued. Sumo, quite naturally, was regarded chiefly for its military usefulness and as a means of increasing the efficiency of the fighting men. Later in the hands of the samurai, jujitsu was developed as an offshoot of sumo. Peace was finally restored when the different warring factions were united under the Tokugawa Shogunate in 1603. A period of prosperity followed, marked by the rise to power of the new mercantile classes. Professional sumo groups were organized to entertain the rapidly expanding plebian class and sumo came into its own as the national sport of Japan. The present Japan Sumo Association has its origins in these groups first formed in the Edo Period.