Even during the return in time to tell the story of Alma’s people, Mormon finds he has to also return to an earlier event to explain the current state of affairs. The army that had pursued Alma’s people had become lost, but while they were lost, they came across the priests of Noah. The priests and their stolen wives had begun to till the land. As with other occasions, the women plead for mercy on their husbands, and it is granted.
There is no way to know how much time passed between the abduction and the time they were found, but perhaps it was sufficient that some of the women were pregnant and had learned to live with their new husbands, perhaps even to love them. Certainly, if they were to have children, there were bonds created that were important, thus the women would plead for their husbands in spite of having been their captives.
Mormon tells his short aside because of the role of these priests in the rest of the story of Alma’s people, a role that, otherwise, would have had no explanation.