The Deadlands represent a vast swathe of undeath in Dark Faerun. In these lands the dead do not lie quietly in the ground; they wander.
After the death of Bane and the disappearance of Myrkul, Lord of Bones, during the time of troubles, Jergal, the Lord of the End of Everything, the seneschal of the Lord of the Dead, found himself unable to perform his duties effectively. Tasked with impassively marking the deaths of all things, as an avatar his influence was narrowed to a sphere he found impossible to work within. As such, Jergal gathered his clerics to himself and splintered his essence into 206 pieces. Before the eyes of his priests, Jergal sloughed off skin and collapsed into a pile of dust and bones. His followers took those 206 bones and fashioned a reliquary for each one, big and small, and carried them far and wide. Where their feet touched the ground, the dead refused to stay dead, and thus was Jergal’s awareness and influence greatly expanded.
As time passed and his followers spread a path of undeath, the regions they inhabited began to become known as the Deadlands. East of the The Empire of Twins and west of The Char, the Deadlands present a buffer between the archdevil’s society and the corrupt demonic influence of the Char. The priests of Jergal found themselves joined by other necromancers; clerics, wizards and sorcerers who dabble in the undead arts. Most joined together, forming cabals and reigning in the undead hordes. The Empire of Twins, seeing the value of such an army, approached its mortal masters with an offer; guard our borders against demons of the Char and provide us safe passage through your lands, and we will supply you with food, riches, and slaves. The cabals agreed, for the Deadlands itself has trouble supporting crops, and their resources had become strained.
There are some individuals, however, associated with no necromantic cabal. These wielders of death magic roam the Deadlands or secure themselves in lonely keeps, accruing undead followers and preying upon those who disturb them.