Curse of Undeath

Since time immemorial, Sanzeia has known the ravages of what is commonly referred to as the Curse of Undeath. Necromancy has been viewed unfavorably by most cultures across Sanzeia (with a few notable exceptions such as the Neatherese) and while most undead are raised and commanded by a necromancer for an (evil) purpose, the Curse of Undeath means that undead are at times randomly and spontaneously generated. In general these so-called "wild undead" are mindless and do not leave the area where they arose and therefore are only really considered a threat to adventurers or grave robbers. However, there have been documented cases where a particularly strong undead will arise naturally and begin creating more undeath, these events if not stopped quickly can reach epidemic proportions and are thought to have been the cause of multiple lost civilizations.

Mythological Cause

The common mythological root of undeath is considered to be a world spanning curse placed upon all of Sanzeia by a being of immense power and malice. Where traditions diverge is in attempting to name the entity responsible. The most commonly accepted explanation is that in the aftermath of the Fall of the Giants, the betrayer God was banished from Sanzeia, and before his name was erased from reality he places 12 curses upon all of the world. Cults to this fallen deity (that have not been purged) typically espouse a desire to destroy the world and its order and the undead, seen as a perversion of the natural order of things, are considered agents of chaos. Thus while no actual evidence of the connection exists, the curse is often considered to be the last spell of the Betrayer as he was banished from Sanzeia.
This interpretation has an issue particularly in the face of the death god, Raz'ka who's hatred of undead is legendary. His roll in the Thirteen predates the fall of the betrayer and thus is used as a basis to attribute the curse to an even older vanquished entity, most typically something powerfully planar like an fiend or elemental. This belief posits that undeath is caused by extra planar energy manifesting in the material and using the bodies of the once living to anchor itself to the material.

Social Impact

It is a common belief that those buried in ways beneath their station are more prone to rise as the undead, as well as those who were evil in life. Although the practice largely fell off in the past 1000 years or so, it was a tradition among humans and many elves that anyone of high enough standing in life had to be buried with proper honors, even if they were villains, shamed, or disgraced. These tombs were often sealed from the outside as a matter of praticality and final insult should the evil being within rise as  undead.
The defensive threat caused by the potential of any graveyard becoming the source of an invasion, has lead to a tradition of such spaces being built not only with walls, but usually in a gully, valley, or some other place where defenders can easily take the high ground. Gravekeepers while their primary duties are with the burial of the dead and maintenance of burial sites, were at least in the past highly militarized.

Type

Metaphysical, Supernatural