Qualong Undead Invasion
From Dragon Eye Atlas
The Qualong Undead Invasion was a mysterious desaster that occurred in the autumn of 66 AV. It is named after the ruined city of Qualong from which many people believed or still believe the undead originated despite later evidence making this theory unlikely.
What is known is that in the north of Sasanguk, an unknown group of mages conducted an unknown ritual at an old ruin that has been lost in the jungle for hundreds of years. Almost everything about this ritual is unknown as none of the mages survived or could be identified. It is, however, believed that this ritual opened a rift that allowed a large number of undead to pass through.
A second theory contradicts this one and points to Qutup, which seemed to be the center of the invasion and was certainly hit the hardest (nobody survived the invasion in Qutup). There is evidence that something went down in Qutup as the number of bodies found there a year later, when the Mun army arrived, far exceeded the population of the village.
In any case, the undead invasion lasted the entire autumn and winter and hit almost every village in the south-east of Cheor Land. An estimated 4,000 people were killed by the undead, though none are reported to have risen themselves as such creatures afterwards. While the total losses are just 2% of the population of Cheor Land, it is a large province and most parts were unaffected. In the affected areas, about a quarter of the population perished and several villages were wiped out entirely.
Despite winter not meaning snow and ice so far in the south, it took several months until Mun armies were gathered and reached the area. By this time, most undead had already vanished wherever they came from. The armies as well as several parties of adventurers destroyed the remaining undead, several thousand strong, and aided in the repairs and burying of the dead before returning north.
During the height of the invasions, peasants had armed themselves with everything they could find and fortified their villages, or fled them. Before the main armies arrived, several smaller military contingent from southern castles protected individual villages, but were too few in numbers to cover the whole area.