Mormon gives us the essential political geography and the likely source of the coming Lamanite/Nephite conflicts. The Nephites control land south of the narrow neck and they separate Lamanite lands from the territories even further north. Thus, the Nephite-held territory lies directly in the line of any possible Lamanite northerly expansion. Indeed, reconstruction of the movement of Maya languages suggests that just such a northerly push into lands previously held by Zoquean speakers.
Additionally, Sorenson’s correlation places the Central Mexican basin north of Nephite territories. Thus, any trade corridor between Central Mexico and the Maya would run through Nephite-controlled land. Such trade possibilities would be a strong enticement for the Lamanites to move into Nephite lands or at least control the trade routes.