Nahom, A Book of Mormon site has been found
In Lehi's travels through the Saudi Arabian peninsula, he named many locations (Laman, Lemuel, etc). One location, however, seems to already have had a place name: Nahom. It is the location where Ishmael is buried and his daughters mourn for him. According to Nephi's description of their travels, this Nahom is located somewhere in southwestern Arabian peninsula.And sure enough, This year (2000) it was announced that an altar was found with the name, "Nahom" on it! It dates back to Lehi's time (600 BC), and it is in the location Nephi described.
Such information was not available in Joseph Smith's day. In fact, this area has only been researched in the last few years.
For more info on it, see: Gregory Witt's Lehi's Trail website