These verses serve to close one story and begin another. It is a subtle transition because it uses the events of the previous story as the background for the next. The tensions with the Lamanites were high, and after three significant defeats, the confidence of the people of Limhi was low. Not only was there fear of the Lamanites, but the former priests of Noah had created deadly mischief before, and there were missing grains and other things that were ascribed to the thieving priests.
All of these events will explain how it was that when Limhi was outside the city that he had armed guards when Ammon and his brethren came into the land. At this point, the record of Zeniff catches up with the events that Mormon had already recorded using Ammon’s record, perhaps as entered into the large plates of Nephi.