>>718526162
In Rebirth, they tried to flesh out the various towns more. But it's important to remember that Shinra more or less controls the entire planet in FF7.
According to Rebirth, there were originally two major powers, the Junon Republic and Wutai. Eventually, Shinra started amassing more power and annexed Costa Del Sol and Kalm, kickstarting the Junon War. Shinra won and took control of not just Junon territory, but most other territories as well. Wutai was also a major power, but it seems they initially stayed out of the conflict as it seems they didn't have a particularly close relationship with Junon. It was only once Shinra started eyeing Wutai's territory that the war happened. Right now, the only major superpowers in FF7 are Shinra and Wutai. There are no other kingdoms or republics, Shinra controls almost everything. If any other kingdoms did exist, they either would have been snuffed out by Shinra decades ago or they'd have allied with Wutai in resistance.
Even if you ignore all the Rebirth retcons, the initial establishing lore of the original PS1 game was that Shinra controlled most of the world. Why do you think there are Shinra-owned mako reactors everywhere? Those reactors are the proof that Shinra controls that area.