orichalcum

So, all over the Roman Empire, there were four teams, two main ones, the Blues and Greens, and two lesser ones, the Reds and Whites. If you did well on the Blue chariot racing team in Podunkopolis, your contract might get bought by the Green or Red (or Blue) team in Cosmopolis, and you'd switch loyalties. Blues and Whites would generally work together, as would Greens and Reds. Within a city, the teams served not just as factions of fans but as de facto clubs and political associations, patronizing dancers and chefs as well as chariot racers. So, essentially, the sponsor group, but also the racers themselves.