[quote=@Muttonhawk]
Galbar appears to be relatively small compared to Earth in terms of territory if, for instance, Vetros controls the entire firewind desert. Local maps are few and far between. It's probably easiest to take it as interpretation then accurate measurements.
[/quote]

IIRC Galbar is supposed to be slightly smaller than Earth (or was that the Galbar from the prior Divinus?) and yet have a density such that gravity remains equal to that of Earth.

Vetros and Alefpria have so much divine involvement that they can't really be held up as examples. Whilst Vetros (as of when I write this, though it will change soon) still uses stone weaponry and doesn't have any extensive metalworking, the city controls many villages up and down the Mahd river and is somewhat developed. It's been in such a state for several hundred years, as canonized in one of the Yara posts that lists some of the past Priest-Kings. 

That being said, the majority of the Firewind is just empty space thanks to it being mostly desolate and also because Zephyrion and the djinn intentionally drove away everyone else. Nomads like Y'Qar's band are the only ones that stray far from the Mahd. It's not like Vetros is the Persian Empire with huge swathes of land and dozens of different cultures under its control.

And since Vetros was artificially advanced by Ventus and so on, it can reasonably exist as such and not make the timeline with Gerrik seem invalid. Maybe Gerrik just invented fire for he Hain whereas it was already widespread in Vetros and Alefpria. In any case, this is why I dislike pinning a certain invention to a specific individual or exact date. It leads to somewhat inexplicable situations like the one BBeast just mentioned with Gerrik still being alive and relatively young. (Although I think an easy solution to the paradox is to just say that Gerrik is ancient by Hain standards because Teknall slowed his natural aging)