At one time two thousand young men whose parents were converted Lamanites did valiant service for their country and their religion.

There isn't room to tell you about the story here; but you may read about it in the Book of Mormon, beginning with the 53rd chapter of Alma.
When Nephi separated from his brethren, he went north and settled in a place they called the Land of Nephi; but after a time the Lamanites again annoyed them so much that the Lord told Mosiah, who was their leader then to take the more faithful part of the people and again go northward.

This they did, and found a city called Zarahemla which had been built by a people who had also come from Jerusalem at the time that city was destroyed.

The Nephites joined with the people of Zarahemla, and for a long time this city was the capital of the Nephite people.
In time the Lamanites occupied all of South America except a small part in the north, on which the Nephites lived.

The Nephites' land also extended far up into North America.
A little over six hundred years after Lehi landed on this continent, Jesus appeared unto some of the righteous.