Don't you think using the term "city" to name small regions in the provinces will be problematic when it comes to simulate the nomadic (or semi-nomadic) life-style of the steppe people (e.g., Scythians or Xiongnu)?
Will there be adaptations of this organization for these different kinds of governments/social structures?
There's no reason to do something that drastic: just have the localization call it something else than City if you're a Nomad. Though what it could be called is another issue.