The threat of death that hung over Alma would likely be extended to any of those who believed on Alma's words. Since Alma was now preaching against the social, religious, and economic rule of Noah and his remaining priests, he would be even more hated and hunted than when he first fled the court during Abinidi's sham trial.
The "borders of the land" had to include Mormon, since we are told explicitly that they were in Mormon. However, Mormon is still apparently attached as part of the greater land associated with, or beholding to, Lehi-Nephi. They have gone far away to avoid problems, but not so far away that they have completely lost connection with the city, as we will see in the next verse.
Textual: This verse is a transition from the story of Alma's people to the next story, the destruction of Noah. It uses the idea of the remote location of Alma's people as tie that moves to the armies of Noah searching for them.