Demography: Mormon’s description is more literary than literal. He is, at most, allowing only the four hundred years between this migration and his own time for this people to have multiplied to the point where they “cover the face of the whole earth.” While the people in the land northward certainly did cover the whole face of the earth in Mormon’s time, they were not all descended from this smaller group of dissident Nephites. Mormon is taking literary license with history to link these dissidents with the collapse of the Nephite civilization in his own time, thanks to the Gadianton robbers of Mormon’s own day.
Geography: I argue that we should not read as geographic references Mormon’s description “from the sea south to the sea north, from the sea west to the sea east.” These four seas, each in at a cardinal point, cannot be literal references except for an island. Thus, rather than reading this passage geographically, we should see it as a literary image expanding the idea of the “whole face of the earth.” Mesoamerican peoples symbolically centered themselves in a universe that existed inside the four directions. The later Aztecs conceived of their world as completely surrounded by water. Their name for the earth was Anahuac or a land ringed by water: “Completing their division in the horizontal plane, toward the four corners of the world, they conceived of this great disk of the world as surrounded by water.” Thus, Mormon is repeating, with a literary flourish, the “whole world” concept.