The Book of Mormon states that in less than 30 years from Lehi arriving in America, the population had multiplied so rapidly that they had to be divided into two great “nations” (see Introduction to the Book of Mormon, 2024 LDS.org edition).

Even the most rapid human reproduction could only have a few dozen people in this amount of time. Most of them would still be infants or children, and about one-third of them would be elderly.