I just started reading the John the Eunuch mystery books which are set in 6th century Constantinople, and in the background of some of the street scenes there are Blues and Greens wandering around. Wikipedia tells me they were a couple of chariot racing rivalry gangs that dabbled in theological debates and adds "See also: Hooliganism." Wikipedia also mentions Reds and Whites but then says they didn't matter (and they haven't shown up in the book either.)
Now this is definitely enough to whet my appetite, but Wikipedia, as usual, doesn't tell you much more. So who were these sports gangs? What political/theological positions did each side take? Was there a nationality divide or was it more mixed? Was there a class divide? Was the whole sports thing more of a front for political factioning or was it truly a natural sport-theology combo?
Ooo, I've almost finished that series myself! Let's see if I can actually remember how these factions worked.
The Blues and the Greens (and the Reds and the Whites) were chariot racing factions at the Hippodrome in Constantinople, but they also had real political/social impact on the city itself, much like gangs would. Originally, all four factions started out relatively equally, but by Justinian's reign the Blues and Greens had absorbed the two smaller factions and they were really the only important ones. At the specific period these novels are set, the Blues were definitely the "Imperial" team (favored by both Justinian and Theodora, though she was the daughter of a Green bear-keeper) whereas the Greens held more popular appeal. I don't think there was that much of a geographical/nationality divide, since I only know of these factions in their capacity to affect Constantinople itself, but I'm sure there were both similar analogues to the capitol's factions throughout the empire and that the chariot racers employed by the factions could come from pretty much anywhere.
In terms of political vs. sport/theological interests, it seems kind of hard to differentiate both aspects from the influence the factions actually exerted. The Nika Riots (which are actually the setting of one of the later books in this series) were caused when the Blues and Greens actually agreed about something, which caused so much political upheaval Justinian seriously considered abandoning the city. There was definitely a religious element to faction support/membership, but I'll let someone better-versed in Late Antique theology tackle that. At the same time, though, it's not really like the factions became important because of their various political machinations - they were primarily popular for their sporting achievements, and the intrigue came after that.
Originally they were purely sports fans, and blue and green were the colors worn by favorite charioteers, but the gangs grew bigger and more powerful and turned into something a little more political. Justinian complicated things when he became emperor. Previous rulers maintained a carefully cultivated air of neutrality at the Hippodrome but Justinian made no secret of his fan of the Blues. He also used the network of Blues fans to keep him up to date on the goings on of the city. Sort of part intel operation part gossip network.
The Blues and Greens started getting too powerful and Justinian decided to curtail both their privileges because of a rise of factional violence during a period of instability over high taxation (Justinian was always fighting a war somewhere, sometimes 2 or 3 and needed money). The crackdown on Blues and Greens was the straw that broke the camels back and the city rose up in a riot that started when Justinian took his seat in the stadium and people started calling him out publicly (a shocking turn) and things escalated. The Imperial guard managed to capture the ringleaders and execute most of them, but they botched the hangings of the final two (one Blue, one Green) and some monks hid them in a church while the crowd demanded mercy. Justinian called for new games to try to get things back to normal but the Blues and Greens united to scream at Justinian in a public expression of rage as soon as he entered the Hippodrome.
Justinian hid in his palace and the Blues and Greens stormed the city prisons, women took to roofs to pelt guardsmen with tiles and the patricians sided with the rioters and armed them hoping to eliminate Justinian. The riots spiraled so badly out of control most of Justinian's advisers counseled him to flee the city. His wife Theodora talked him into standing his ground and dying if necessary. Belisarius was in town and a group of Scandinavian mercenaries had just arrived ready to ship out to the frontier and Belisarius took command and marched into the city. He cornered the rioters in the Hippodrome and slaughtered 30,000 of them. That was the high and low point of the Blues and Greens as a political force, the Nika revolt. It was named Nika because that's what they chanted to their charioteers in the Hippodrome, and what they flipped and shouted at Justinian at the start of the second riot. They reorganized, but as the Byzantine Empire started shrinking after Justinians reign, and lost population from wars and plague deaths there just weren't as many people to watch sports and get rowdy.
To look at your questions these were just sports gangs that got embroiled in politics. They started as European style football hooligans though. Some have suggested there were theological divides between them but there's no real proof of this that I am aware of. They probably got involved in theological debates because the Byzantines were very into that as a whole, but a solid Blues believe this, Greens believe that line is very hard to establish (some older books do claim the Greens were Monophysites and the Blues Orthodox). There was no nationality divide, they were all Byzantine, or Romans from the city.There was a class divide, the Blues and Greens were commoners, one of the reasons I gave the mini Nike Riots history was to highlight the alliance between them and patricians, and the sheer oddity of Justinian being a Blue. The sports thing was not a front, these were fans of rival charioteers who sort of morphed into more powerful gangs just because of the numbers and affiliation gave them weight in the city.
I don't know of a good specific history of the Blues and Greens, but if you want to brush up on Byzantine History a bit Lost to the West by Lars Brownsworth is a nice place to start.
hi! another response for you here: