The Book of Mormon is a spiritual history. Though it records events that are historical realities, it chronicles such history only insofar as it is germane to its central purpose. It is a theological treatise, the saga of a message. Its sole purpose is to bring men to Christ.
The small plates (1 Nephi through Omni) deal almost exclusively with the things of God, recounting the ministry of the early Nephite prophets (see 1 Nephi 6:3; 1 Nephi 9:3). The small plates contained sacred preaching, great revelations, and prophecy.