Chronological: The four hundred years would be 391 A. D. This is fifteen years after the battle at Cumorah. We have a hiatus in the writing on the plates that occurs at some time during these fifteen years. Since we don’t know how long it took Mormon to finish his writing after Cumorah, we cannot judge precisely the length of the hiatus, but it seems reasonable that it would be ten years at the minimum, and probably longer. During this time we have no information on Moroni’s activities. We may assume that he has been able to find a way to exist without suffering the detection that the rest of the survivors did.