The Road to 5.0

[Theodric]

The situation with Goug is a different matter entirely. That happened much earlier on in the timeline. The lore book is specifically referring to their time spent in Ilsabard and how they were forced out of the fertile portion and into the treacherous wasteland to the north. So if it does turn out that Goug is the origin point for Pureblood Garleans then they lost not one but two homes. One to whatever disaster rendered Goug unfit to inhabit and the second to persecution in Ilsabard. As it stands, we need to await the conclusion of the Return to Ivalice story arc to get the full details.

The lore book does not cover anything post Heavensward. The upcoming second lorebook, however, will.

-snip-

Their default home is a wasteland that cannot easily support them, thus expansion was a necessity to improve their quality of life and prevent them from dying out. Had they not expanded, they would have been at the mercy of the harsh climate and deposits of ceruleum. A particularly poor harvest or sudden attack could have easily wiped them out or at least put a considerable dent in their already small numbers. A better comparison than Nidhogg would be how the Hyur migrated to Eorzea and went to war with the Elezen, shifting the demographics of Eorzea and kicking off events such as the founding of Ishgard as a consequence. The Ishgardians, at least, had the luxury of fertile land...at least until the events surrounding Dalamud brought ice and snow to the entire region.