It’s common-place for SF writers to write about the asteroid belt in a sort of diffuse manner, without any real details that would help fix the features of the belt in your mind. There is a “structure” to the belt, as can be seen in the illustration below:
The numeric part of each asteroid’s name indicates the order in which the asteroid was discovered. In general, of course, the largest ones were discovered first. So, naturally, Ceres was the first discovered, then Pallas, Juno and Vesta, etc. Each of these, as well as many others, could be basis for a belt-based nation-state, or mini-nation.
As you can see, the belt extends from Mars out towards Jupiter. Some asteroids orbit nearer the inner edge, some in the middle (like Ceres), and some further towards the outer edge. There’s also an anomaly in the structure of the belt, the so-called Kirkwood Gap, in which far fewer asteroids are found.
All of these asteroids, of course, are orbiting the Sun at different speeds, and may thus be closer or more distant from each other based on where they are in their respective orbits.
Armed with these details, writers should be able to concoct more convincing stories set in the belt than many of the ones I’ve read in the past. Sometimes a little research goes a long way.