Gambling precedes civilization and i kinda believe it's something the people of old used in whiling away time at leisures not until the Romans engaged the gladiator gambling pattern where lives were part of stakes in arena's.
^ That was a bloody sport that Romans found, inside the arena the strongest will survive bit now, it is purely sports but they are the same in the arena. Did you know that NBA sports have 29 arenas? The history of sports gambling has been civilized into a modern one though they have the same sports it has a different approach it is more friendly sports than what we are now compared to Roman's time.