Sumo was mentioned in Nihon Shoki, one of the earliest texts in Japan, under its earlier name sumai, from the 8th century A.D. However, these early forms would not be sumo as it is known today, as in many cases the wrestling had relatively few rules and unarmed fights to the death were still referred to as "sumo".In addition to its use as a trial of strength in combat, it has also been associated with Shinto ritual, and even today certain shrines carry out forms of ritual dance where a human ceremonially wrestles with a kami (a Shinto divine spirit). It was an important ritual at the imperial court. Representatives of each province were ordered to attend the contest at the court and fought. They needed to pay for their travels themselves. The contest was known as sumai no sechie, or "sumai party."

Over the rest of Japanese recorded history, sumo's popularity has changed according to the whims of its rulers and the need for its use as a training tool in periods of civil strife. The form of wrestling combat probably changed gradually into one where the main aim in victory was to throw one's opponent. The concept of pushing one's opponent out of a defined area came some time later.

It is believed that a ring, defined by more than the area given to the wrestlers by spectators, came into being in the 16th century as a result of a tournament organized by the then-principal warlord in Japan, Oda Nobunaga. At this point wrestlers would wear loose loincloths, rather than the much stiffer mawashi of today. During the Edo period, wrestlers would wear a fringed kesho-mawashi during the bout, whereas today these are worn only during pre-tournament rituals. Most of the rest of the current forms within the sport developed in the early Edo period.
Professional sumo (大相撲, ōzumō^?) can trace its roots back to the Edo Period in Japan as a form of sporting entertainment. The original wrestlers were probably samurai, often ronin, who needed to find an alternative form of income.

Nations adjacent to Japan, sharing many cultural traditions, also feature styles of traditional wrestling that bear resemblance to sumo. Notable examples include Mongolian wrestling, Chinese Shuai jiao (摔角), and Korean Ssireum. Examples of Chinese art from 220 BCE show the wrestlers stripped to the waist and their bodies pressed shoulder to shoulder.^[1]