Geographical: Mormon gives us some definitions of lands. These are gross divisions in the land and serve to mark the basic conceptual outline of the world from a Nephite standpoint. As with virtually all peoples, the Nephites are in the center, and directions are given relative to where the Nephites are. Thus the land south is south of the land of the Nephites, and the land north is north of the land of the Nephites.
In particular, the land south is defined as the land of Nephi. The traditional region of conflict in Nephite history since the time of their arrival in Zarahemla has been the southern lands. These were the lands of first inheritance, those into which Lehi has lead his family. The Nephites had abandoned them with the flight of Mosiah I from the city of Nephi.
The land northward is here given as the land of Mulek. Mormon tells us that this land is named because Mulek came into this land. This should not be confused with the land of Zarahemla which is the land where Mosiah I met the descendants of Mulek. The land of Mulek is farther down the river valley, and just over the narrow neck of land. It is the introduction to the land northward, and the beginnings of the land of desolation, which describes the ancient Jaredite homeland.
Once again we need to ask ourselves why Mormon is giving us this particular piece of information. He is subtly moving our focus from the current lands to the lands northward, and in this particular case, he makes certain that this land is linked to the ancestral founder of the people who later inhabited Zarahemla. The reason for this is Mormon’s northward focus. He is connection us to the land northward, and in particular to the type of people who inhabit that land. By focusing on the ancestor Mulek, he focuses on the ancestors of the Zarahemlaites, and probably does so because his intent is to highlight the cultural/linguistic connections of the early Mulekites with the remnants of the Jaredites. This cultural/linguistic focus on that region of the land northward will continue to be important through the end of the Book of Mormon.