So long as you do it tastefully and in a plausible manner than I don't think many people will have much of a problem with it. Eorzea and the lands beyond are much, much bigger than what the game world portrays after all!
I'd be very surprised if there weren't all sorts of different outposts and villages throughout Eorzea that we don't get to see in-game due to mechanical limitations. I'd avoid anything too major - such as the creation of additional city states - but if you keep things simple I can easily see it being credible both IC and OOC.
I'd be very surprised if there weren't all sorts of different outposts and villages throughout Eorzea that we don't get to see in-game due to mechanical limitations. I'd avoid anything too major - such as the creation of additional city states - but if you keep things simple I can easily see it being credible both IC and OOC.