Sumo wrestling has its roots
in the Shinto religion. The sumo matches were dedicated to the
gods in hopes for a plentiful harvest. The oldest written records
of sumo wrestling, date back to the eighth century. But it is
most likely that it is more then 1500 years old. Since the Japanese
didn't start using written records until the eighth century, we'll
never be sure. 
Although, ancient paintings show that the origins of sumo wrestling are very old. Sumo paintings from the eighteenth and nineteenth century prove the popularity in the past. Sumo wrestling in its early days was a lot more violent then it is today.
During the last twenty years, sumo wrestling has survived, even outside of Japan. Akebono, an American born in Hawaii, became the first American champion to reach the highest rank. It surprised many Japanese and
This is a sumo wrestler standing on the ring, scratching his belly-button.
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Americans that someone not native to Japan could excel so well in this Japanese sport. Since Akebono was so successful, more international competitors are entering the wrestling ring. All of them are aware that they are participating in a sport that is much older than most of the countries they live in.
Sumo wrestling is the traditional and national sport of Japan. Baseball and soccer are close seconds, but sumo wrestling still seems to be the favorite in Japan.