After the repetition that there had been three years of peace, Mormon begins a completely different story. To this point, he has discussed Benjamin’s speech and noted that Mosiah2 was seated as king, but he has given nothing of Mosiah2’s actions. The very first event that he records for Mosiah2 picks up a story that had been lost with the first part of the book of Mosiah: the people from Zarahemla who had returned to the land of Nephi. We know the beginnings of this story only from the book of Omni, where Amaleki give the basics of the story, perhaps because his brother was one of those to go (see Omni 1:27–30).
We do not have any textual dating to know when they left, but between the time they left and this indication three years after the seating of Mosiah as king, there was sufficient time for Zeniff to create his colony and pass away, for his son Noah to expand the city with large building projects, and for Limhi to take over after his father, Noah, had been killed. Later evidence will suggest that they left during Benjamin’s reign, which only serves to let us know that Benjamin had a relatively long reign.
King Mosiah2 picks sixteen men to go. If we accept a Mesoamerican background for the Book of Mormon, it is possible that the usage of the specific number sixteen (representing 4x4, with the number 4 being a sacred number) is intentional. Why mention the number rather than generically say that several men left, unless there was some meaning to the number?
This begins a complicated section of the Book of Mormon. It involves actions in the land of Nephi, not Zarahemla, and will cover both events in the narrative’s current timeline as well as extended flashbacks before both time and events return to Zarahemla in our Chapter 25 of the book of Mosiah.