Military: Battle
The denizens only learned of it when the undead horde was already attacking them. This horde of undead came from the West and took several years and many sacrifices to finally fight off.
Scholars are still unsure exactly what caused the undead horde to appear, although many argue that Li'gnax pulled the undead away from the border between itself and Li'guth, the world tree that would appear the year after. While the lizardfolk that were exploring the Blackmist Peaks could only look upon the undead horde crashing in like a flood of water and consuming the marshes, they had no way to contact any of their brethren. The initial settlement they had made when they first arrived in the Inkwater Marsh quickly got overrun before they could even reach it and Chessenta only barely held, although this settlement too was far out of their reach before it got surrounded by undead. After the undead had been defeated or scattered the lizardfolk in the mountains could finally decent and make contact with Chessenta. Here they told of what they had seen and vowed to never let it happen again. To this end, a series of signal fires were constructed on top of the mountains with the ability to signal various things should a similar disaster ever happen again. To this day the signal fires still remain unused by the lizardfolk still tend to them and repair them when broken in case they are ever needed again.