The introduction of the Book of Mormon states that the Nephites, Lamanites and Jaredites were from the groups scattered at the time of Babel, where God confused the languages and caused the people to separate, so they would no longer congregate and try to build structures to invade heaven.
Here are summaries of these groups:
NEPHITES
According to the Book of Mormon, a Nephite is a member of one of the four main groups of settlers of the ancient Americas. The other three groups are the Lamanites, Jaredites and Mulekites. In the Book of Mormon, the Nephites were a group of people descended from or associated with Nephi, the son of a prophet who left Jerusalem at the urging of God c. 600 BC[1] and traveled with his family to the Western Hemisphere, arriving in the present-day Americas c. 589 BC.[2] The Book of Mormon describes the Nephites as an initially righteous people, who eventually fell into wickedness and were utterly destroyed by their brothers the Lamanites c. AD 385.[3] Helaman 3:8 reads: “And it came to pass that they did multiply and spread … to cover the face of the whole earth.” According to Mormon 1:7, the land “had become covered with buildings.”
http://en.wikipedia.org/wiki/Nephite (WIKIPEDIA: footnotes can be verified at link)
LAMANITES
The Book of Mormon describes the Lamanites as descendants of Laman and Lemuel, two rebellious brothers of a family of Israelites who crossed the ocean in a boat around 600 BC. Their brother Nephi founded the Nephite nation. The Lamanites reputedly gained their dark skin as a sign of the curse for their rebelliousness (the curse itself being the withdrawal of the Spirit of God), and warred with the Nephites over a period of centuries. The book says that Jesus appeared and converted all the Lamanites to Christianity; however, after about two centuries, the Lamanites fell away and eventually exterminated all the Nephites. By the end of the Book of Mormon, the Lamanites were defined less by their skin color than by their lack of Christianity. Many Mormons believe that the Polynesian people originated from the descendents of Hagoth who led his people off on a ship and was never heard from again. Although Hagoth was a Nephite, these Mormons regard Polynesians as Lamanites.
http://en.wikipedia.org/wiki/Lamanite (WIKIPEDIA: footnotes can be verified at link)
JAREDITES
The Jaredites are a people written of in the Book of Mormon, principally in the Book of Ether. In the Book of Ether, the Jaredites are described as the descendants of Jared and his brother, at the time of the Tower of Babel. According to the Book of Mormon, the people fled across the Ocean via boats and established an ancient civilization in the Americas. The existence of the Jaredites is doubted by non-Mormon historians and archaeologists.http://en.wikipedia.org/wiki/Jaredites (WIKIPEDIA: footnotes can be verified at link)
Problems with the existence of these races:
- Historians, anthropologists and archaeologists do not support the existence of such people in Central America.
The existence of a Lamanite nation has received no support within mainstream science or archaeology. Genetic studies indicate that the indigenous Americans are primarily from northeast Asia, and the Polynesians are from southeast Asia. This has led many Mormon apologetic scholars to hypothesize that the Lamanites were a small nation that merged with the indigenous population of northeast Asian origin and left no clear traces surviving into the modern world. Within the culture of Mormonism, indigenous Americans and Polynesians are still often called "Lamanites", but the practice is waning. WIKIPEDIA
- Egyptians built ships around 3000 BC, so it's possible these groups could have sailed. However, the thought of traveling across the ocean was unheard of. Ships were built to sail down rivers or local seas, not to make huge expeditions.
- The area they lived in was not crowded, so there was no need to travel far. A week's journey could separate you easily from other tribes.
- DNA evidence shows that indigenous people to Central America do not have Jewish blood in their system.
- The Book of Mormon says they scattered at the time of the Tower of Babel and that the tribes arrived in America around 600-500 BC. Babel occurred much earlier. While it's hard to date, Babel had to occur before 1000 BC, maybe even 3000 BC.
- 600-500 BC is the time of the Babylon/Persian empire in Jewish history. So did they leave during Babel or during the Babylon/Persian invasions?
- If these groups arrived in America, then Columbus (or the Vikings) did not discover America.