“All these things” that the sons of Mosiah have been doing were attempts to rectify the effects of their preaching against the church in the land of Zarahemla. Because of their privileged position as the sons of the king, they had probably been instrumental in attracting many away from the church in Zarahemla. Therefore, they took their first mission to those whom they had most directly hurt.
This next section describes a secondary “mission.” After the sons of Mosiah (and “a small number with them”) attempt to rectify the damage they had caused in Zarahemla, they ask to mount a mission to the Lamanites. Why the Lamanites?
The traditional Book of Mormon interpretation would suggest the Lamanites are the only other people around; if all of Zarahemla were converted, there would be nowhere else to go. Even interpreting “Lamanite” as a term for all non-Nephites, as I do, it might still be considered logical to turn to the Lamanites if all of Zarahemla were converted.
However, I find it likely that the sons of Mosiah and Alma2 during their apostate period had been converted to the religion practiced by Noah and his priests. If this is true, it would be natural for the sons of Mosiah to feel concern for those whose incorrect religion they had so recently espoused. This connection to the religion of Noah’s priests was likely one of the influencing factors in their choice of returning to the land of Nephi for their mission. (Aaron is specifically in the land of Nephi in Alma 22:1.)
Considering how often the Nephites have pejoratively described the Lamanites (e.g., 2 Ne. 5:21–24; Enos 1:20; Mosiah 9:12, 10:12), we might expect that this cultural preconditioning against anything Lamanite would preclude them as possible missionary targets. Yet like Zeniff (Mosiah 9:1), the sons of Mosiah apparently found much good in the Lamanites and now naturally turn to those people to share with them the same joy they have so recently found.