Byzantine empire was based on the Roman government. It had a emperor, senate, (equestrian or nobility) then the plebs poor...slave or freeman. Power was based on land....agriculture in the country...so the biggest and fertile land was a status of power, in the cities the land lords held economic power. The christian church would lead in power as the state religion, the eastern Orthodox church until the invasion of the Turks...
There was one other class, those in the guilds free men with specialized skills that were required, e.g. metal workers had a strong guild. Byzantium had four political parties as to social status..the reds, blues, golds and greens......if forget which is which but when they had games citizens would cheer for their party at the games.
The Byzantine empire was the last to fall surrounded by three sides of water, it just needed a good navy to protect it with fortified coastal cities, then a land army at its vulnerable part. As I said it was not until the Turks with there latine sailing ships defeated the Byzantines, but that is another story..
