Mosiah 23:25

For behold, it came to pass that while they were in the land of Helam, yea, in the city of Helam, while tilling the land round about, behold an army of the Lamanites were in the borders of the land.

While they were in the land of Helam, they were working in their fields around the city. Then a Lamanite army came to the edge of the land.

Here’s what happened: while they were living in Helam, working their fields around the city, a Lamanite army appeared at the edge of the land.