In 1991, though most people didn't realize it at the time, the Oshima stablemaster made a decision that would dramatically alter the course of sumo over the next several decades.
The former ozeki brought six young men from Mongolia into his stable and began a process that has led to the sport being utterly dominated by wrestlers from the landlocked east Asian nation for most of the current millennium.
It almost didn't turn out that way however, as the unfamiliarity of Japan and the harshness of sumo life led to five of the six running away and seeking refuge in the Mongolian Embassy before finally being convinced to return.