Alma 50:13

And it came to pass that the Nephites began the foundation of a city; and they called the name of the city Moroni; and it was by the East Sea; and it was on the south by the line of the possessions of the Lamanites.

The Nephites started to build a city. They called it Moroni. It was by the East Sea. It was on the south by the border of the Lamanite lands.

The Nephites started building a new city. They named it Moroni. It sat by the East Sea, on the southern border of Lamanite territory.