Procopius writing about the fans of two factions of Byzantine chariot racers.
It got to be that being a green or a blue was a precondition for participating in any form of civil life. "You want to buy figs? Well are you a blue or green? Get the fuck out of my stand." God help you if you tried to hold a government post without taking a side.
Eventually there was a sports riot where more than 30,000 people died and they tried to be a little more senisible about how serious chariot races really were after that.