The techniques date back several hundred years, and it is even mentioned in the mythological Shinto texts of the Nihon Shoki from 642.
According to another source, the Shoku-Nihon Gi, the first organized matches occurred on July 7, 734. They were called "sechie zumo" matches, and in the Heian era they were held for the aristocrats. This practice became extinct after 430 years in 1174.
Yet these matches continued on locally and within the ranks of bushi. At community level, they were shrine organized events called "tsuji-zumo". However over time this ran into problems as outside of the organized events, quarrels and arguments became "sumo challenges" and matches would be issued at any time and create chaos. So there was an edict issued during the Edo era to end them.
However, around the same time as the outlawing of community Sumo in Edo, there was a resurgence of Sumo with professional Sumotori (Sumo wrestlers) and the creation of stables, which was formally organized in matches during 1790 under edict from the Shogun. This stemmed from the "bushi" recreational training, which was carried on in tandem with the local contests.
During Meiji the rise of "sport zumo" (just "sumo" now) became popular, which changed with "modernization" and added the rules of sportsmanship, to turn Sumo into a game. This advanced Sumo into the modern age, and while the ritual was still kept, it lost a lot of the original intent and "spirit" at the local level.
There is a connection between the Eba Dojo and the Minesaki-beya, which is housed during the Nagoya Basho at a local Shrine, which has a training ground, or "Dohyo" (which is sacred and not for public use). The communities around Kuwana city all rally to support the Minesaki beya, and they hold annual events for children and teach and interact with the locals.
If you are interested in learning more about Sumo, you can read and study more here or view a plethora of information here. All free.
Also is an in-depth definition found at the Kokugakuin.
There is also several videos on YouTube to watch, as well as the Nihon Sumo Kyokai website.
If you are interested in training with us, please write to firstname.lastname@example.org .