What is the definition of a “Lamanite?” It’s a non-Nephite:
And it came to pass that whosoever would not believe in the tradition of the Lamanites but believed those records which were brought out of the land of Jerusalem and also in the tradition of their fathers which were correct who believed in the commandments of God and kept them were called the Nephites (Alma 3:11)
Thus, the de facto name of those who inhabited Book of Mormon lands prior to Lehi or Mulek was “Lamanite”:
…borders of the land of the Lamanites (Alma 17:13)
…borders of the land of the Lamanites (Alma 21:1)
Some lands became synonymous with, or a subset with Lamanite lands:
13 And it came to pass that when the LAMANITES saw that they could not overpower the Nephites they returned again to their OWN LAND and many of them came over to dwell in the LAND OF ISHMAEL and the LAND OF NEPHI and did join themselves to the people of God who were the people of Anti-Nephi-Lehi. (Alma 25)
Even in modern time the Lord differentiated between Lamanites by birth (i.e. the pre-existing American Indians) and Lamanites by dissension:
48 Yea, and this was their faith—that my gospel, which I gave unto them that they might preach in their days, might come unto their brethren the Lamanites, and also all that had become Lamanites because of their dissensions. (D&C 10)
Why is this important because if there were pre-existing people on Book of Mormon lands that changes our perception of their history completely.
Modelers must be able to show two distinct culture groups with one being much larger than the other, which is precisely what we find in western New York with a larger pre-existing American Indian group – the Hopewell.
The Hopewell people were not the Nephites as some claim they were.
See also: