Historical: This section of the story of the destruction of the Amulonites begins with the statement that many Amulonites perished by fire at the hands of the Lamanites, and then ends with the “balance” of that statement with the prophecy of Abinadi. Mormon’s intent here is to show prophecy fulfilled. From that standpoint, he makes his moral point. As history, it is very unclear how any of this information could have been available to a Nephite historian. These were actions taken out of Nephite-controlled lands, and internal to Lamanite politics. Verse 9 appears to show some knowledge of this event from Mormon’s time, but it is quite unlikely that this very event should have been so dramatically present in Lamanite thinking four hundred years later. As noted earlier, the entire account has the markings of tradition rather than history.
It is possible that there are some known historical events behind Mormon’s explication of the story of the Amulonites. The internal Lamanite tensions leading to the death by fire of various peoples might have a historical touchstone in the inter-city wars that are now known to have occurred in Maya culture. Death by fire was one of the modes of sacrifice, and while not the most statistically prevalent, it was still a mode of human sacrifice. Since the death by fire creates the “balance” with Abinadi’s death, it would not be surprising if Mormon selected this particular facet precisely to make his moral case stronger.