The Sea East was the body of water bordering the Nephite and Lamanite lands on the east, paired in the record with the Sea West. The narrow strip of wilderness that divided the land of Zarahemla from the land held by the Lamanites ran from the sea east to the sea west, continuing along the borders of the seashore and the wilderness on the north by the land of Zarahemla, through the borders of Manti by the head of the river Sidon (Alma 22:27).
As the Nephites rebuilt their waste places and multiplied, they spread until they covered the whole face of the land, on the north and the south, from the sea west to the sea east (Helaman 11:20). Their earlier expansion likewise reached the eastern sea: they went from the land southward to the land northward and spread from the sea south to the sea north and from the sea west to the sea east (Helaman 3:8).