[insert stock Rufus post game post here]
The impression I get from most FF games is that every town basically fends for itself. They're all fortified, travelling is dangerous due to all the wildlife, so everywhere is mostly on its own, even if they're nominally under control of somebody.
Yet...
Wutai had a sophisticated enough war machine to keep up with Shinra for years, enough people were buying coal to keep Corel running, complete with railroad. Cosmo Canyon has complex machinery.
I get the impression that the reason ShinRa and Wutai ever got into a war was because Wutai had possibly had expansionist ambitions, and began trying to take chunks out of the Central Continent. Unprepared for such an invasion, they turned to ShinRa for help.
Otherwise I can't really fathom why ShinRa would have a fuck-off nuke-canon pointed directly in the wrong direction against it's only known enemy, unless Wutai had already seriously taken enough of the CC to be a considerable nuke-worthy threat.
Bur yeah, there's a whole 2,000 years of precious little recorded history.