Alma 50:29

therefore, Morianton put it into their hearts that they should flee to the land which was northward, which was covered with large bodies of water, and take possession of the land which was northward.

So Morianton told them they should run to the land in the north. That land had big lakes. They could go live in the land to the north.

So Morianton convinced them to flee north to the land covered with large bodies of water and take control of that territory.