"And it came to pass that the Nephites had inhabited the land Bountiful, even from the east unto the west sea, and thus the Nephites in their wisdom, with their guards and their armies, had hemmed in the Lamanites on the south, that thereby they should have no more possession on the north, that they might not overrun the land northward.
Therefore the Lamanites could have no more possessions only in the land of Nephi, and the wilderness round about. Now this was wisdom in the Nephites--as the Lamanites were an enemy to them, they would not suffer their afflictions on every hand, and also that they might have a country whither they might flee, according to their desires."
Towards the end of Chapter 22, Mormon takes a break in telling the story of Aaron and King Lamoni's father so that he can describe the division of land between the Nephites and the Lamanites. Then in verses 33-34 he explains why it was important that the Nephites not allow any room for the Lamanites to encroach upon them. As I read these scriptures I realized that Mormon included this information, not only to help us better understand the affairs of the time, but also to remind us of a very important truth: Just as the Nephites realized that the Lamanites were their enemies and that it would be dangerous to allow them any access to their lands, or even the land around them, we should remember that Satan is our enemy and we should not give him access to our lives.
The Nephites didn't stop with prevention, though. They also had a plan just in case the Lamanites did manage to sneak in--their plans included room for them to flee away from the Lamanites. If the Lamanites did attack them, they knew in advance where they could flee for safety. We should follow this example when dealing with Satan and his followers and prepare in advance what our responses will be when faced with temptations and choices.