John Gee and Matthew Roper argue that the Book of Mormon acknowledges non-Lehites in ancient America in light of its use of the book of Isaiah.
John Gee and Matthew Roper, "'I Did Liken All Scriptures Unto Us': Early Nephite Understandings of Isaiah Implications for "Others" in the Land," in The Fulness of the Gospel: Foundational Teachings from the Book of Mormon, edited by Camille Fronk Olson, Brian M. Hauglid, Patty Smith and Thomas A. Wayment (Provo, UT: Religious Studies Center, 2003), 51-65
In this essay we discuss how early Nephites in the time of Nephi and Jacob may have likened the words of Isaiah to their own peculiar situation in a newly discovered land of promise. We suggest that the words of Isaiah inscribed and rehearsed by Nephi and Jacob would have been especially meaningful to Nephi's ancient American audience if there were other non-Lehite and non-Israelite peoples in the land of promise when they arrived. First we will address the common assumption readers sometimes make that the promised land was devoid of inhabitants when Lehi's family arrived in the land of promise. Then we will suggest how the presence of others in the land makes the Isaiah passages in the Book of Mormon more meaningful.