These twenty-four gold plates were a record of ancient Jaredites, inhabitants of the Americas before the Nephites. This particular people left the Tower of Babel at the time of the confusion of tongues. Their prophet-leaders were led to the ocean, where they constructed eight peculiar barges. These were driven by the wind across the waters to America, where the Jaredites became a large and powerful nation. After many centuries, wickedness and wars led to a final war of annihilation. During that final war, Ether, a prophet of God, wrote their history and spiritual experiences on twenty-four gold plates, perhaps relying on earlier Jaredite records

Source: Ludlow, Daniel H, ed. The Encyclopedia of Mormonism. Vol. 1. BOOK OF MORMON PLATES AND RECORDS. New York: Macmillan Publishing, 1992.