as I recall the original treaty between the Kobolds and Limsa was: The Kobolds were given rights to anything that came for under the land (of Vylbrand), where as Limsa Lominsa was given rights to anything from under the sea.
Limsa realized that they couldn't survive off the sea alone and thereby started farms and stuff in La Noscea...
I will state all info is unsourced, but I believe it's from the Titan(Normal) part of the main storyline, or some sidequests around La Noscea