In SE 5083, in the coldest month of the year, an unprecedented and dangerous event occureed; the dead began to rise every night, en masse, seemingly without the intervention of a necromancer.
The following months were exceedingly dangerous, as solutions were sought in all civilized lands. Eventually, each kingdom settled on a means of protection which enables them to keep their population centers safe.
Anyone outside a major settlement now carries a circular kit of runes which repels the undead; some circles are only big enough to contain one person in a bedroll, some are large enough to encompass a full carriage and its horses.