Linked with the rituals of Shintoism , sumo probably originated about 2000 years ago .
Linked with the rituals of Shintoism , sumo probably only became a popular sporting event in its own right in the 17th century .
Linked with the rituals of Shintoism , sumo probably originated about 2000 years ago , but only became a popular sporting event in its own right in the 17th century .