In 16th century Italy a new sport emerged. Well in actuality it's just rugby with bare knuckle fighting, but still.
Calcio Fiorentino is Italy's most violent sport. In fact, it's so brutal, it's only legally to hold three matches a year. The rules to it are simple too: sucker punches are banned, kicking someone in the head multiple times is banned, anything that would result in death is banned, and choking people until they stop breathing is banned. Notice how none of those are technically illegal moves, as long as they are done in moderation.