>>119054946Mormons believe that the a group of Israelites left Jerusalem before being sacked by Babylon. God instructed them to build boats and travel to America. There were three groups God instructed to travel to America (one back in Tower of Babel times), but the Book of Mormon doesn't ever mention "native" groups, so it's assumed that all Mesoamericans are descended from these groups. It isn't ruled out that there were others living there, but it isn't ever mentioned.
The two groups that traveled to America split up almost immediately upon arriving because of ego. They form the Nephites and Lamanites. It starts off with the Nephites being the good guys, but eventually the Lamanites become the good guys. Both groups grow and split off like a million times and they're always changing who's following God and who's in apostasy. Sometimes both are in apostasy.
God's people believe in a prophecy of a savior. Eventually almost all of God's people (at the time) are going to be hunted down when their prophecy is set to expire, but then a mini-apocalypse happens and the whole of the continents are thrown into turmoil for three days. Earthquakes, fires, snakes. Then Christ comes.
Christ, having resurrected appears to the people for a few days and instructs everyone how to live. After he ascends everyone lives in perfect harmony for like 300 years and then it all starts to fall apart. By the end, everyone's been in apostasy for like 100 years, there's massive wars unlike anything seen before, and finally there's just one family of God's followers left, and then one man left. That's Mormon. God instructs him to take the sacred records of his people and go off alone into the wilderness and bury them.
There's a lot more in there, but that's the gist of it. Two groups fighting each other out of tradition and suffering corruption and a few good people trying to keep it together.