It is difficult to find a reasonable explanation for why the armies would travel this immense distance to do battle.In fact, it is difficult to find a reasonable explanation for much of the claims in the Book of Mormon that relate to "civilizations" that lived in fairly recent times and have left absolute zero traces of their existence... except in the Book of Mormon.
It would be kind of like trying to find historical evidence of Hobbits.
HOBBITS AREN’T REAL!?!?
Oh man, the guys in my D&D group are going to be so bummed...