I like how society's changed so much by the time Vagrant Story's events unfold. Back in FFXII, magick was a part of everyday life, crucial to technology and science. Mist permeates everywhere, and palings protect cities from attack. While large amounts of Mist are dangerous, there's generally no harm in people studying and embracing magical powers.
But in Vagrant Story, magical arts are forbidden by law and religion, and Mist has become known as 'The Dark', an omnipresent and corrupting force that's kept out of human cities by Palings. Where colossal airships once sailed the skies on Skystone, it's now a significant feat when someone uncovers the spells to temporarily levitate a small piece of Cloudstone.

Ivalice's complete history would be a fascinating, though I fear sad, tale. Learning, for instance, why magic all but disappeared, along with all the non-human races. If the ancient, captive wyrms and war machines of FFXII are anything to go by, it's a world that's repeatedly pushed itself to the brink of annihilation by constructing impossibly powerful weapons of war, whether living or mechanical.