3 Nephi 3:24

and there were a great many thousand people, which were called Nephites, which did gather themselves together in this land. Now Lachoneus did cause that they should gather themselves together in the land southward, because of the great curse which was upon the land northward;

There were many thousands of people called Nephites. They came together in this land. Lachoneus had them meet in the southern land. This was because there was a great curse on the northern land.

Thousands upon thousands of people—all called Nephites—gathered in this land. Lachoneus made them gather in the southern territory because of the curse on the northern lands.