This met the dictates 'of the Ius Fetiales, that is to say it meant that the Carthaginians started it and it touched off what we call the first Punic War.
For one thing the deaths of Aztec and Incan rulers touched off wars which made it easier to spread disease, because you know, the number one way to catch smallpox is via hand-to-hand combat.
Similar soot can still be found in ancient rocks from volcanic fires of 66 million years ago, a record of the cataclysm touched off by an asteroid at the end of the late Cretaceous epoch.