The valley that holds the Land of the Living was once another barren valley in the tundra, home to scarcly any creatures or plants. A shift in magma in the depths of the earth began to heat the waters in fissures deep underground to create numerous hot springs and geysers. The the mist rose to kiss the high hills around the valley untill it spills over and disipates to the winds.
As wandering people began to discover this oasis of warmth in the frozen wastes, they also began to notice the mist’s strange effect on things. They would try to hunt for food, only to loose arrow after arrow and watch with amazement as they were pushed out by the creatures healing powers. Only shots that ended the quarry’s life instantly would also end this healing process. This process was so remarkable that after some time they found they could even capture a live buck, use thier axe to suddenly strike off a leg, and in the time it took them to prepare the leg to cook, the agitated buck once again possessed four strong legs.
Civilizations grow and in time this remote camp of misguided arctic hunters became a villiage, then a settlement, and finally a city. It became appearent that this healing mist only works on animals, for the crops that grew in the warm moist enviroment would not sprout new fruit when the ripe one were harvested. With a finite amount of land to grow crops on, the Khan of the valley decided to send out parties of warriors to find the best crops to fill his valley. Three important things happened from these parties wanderings: First, a mix of grains and trees were brought to the valley to fill every acre with plants. Second, word of the valley’s amazing mist reached the outside world. Third, the warriors of the Land of the Living found that they would not heal any faster than anyone else outside the mist. Of the twelve parties sent out, only four returned, and all suffered the losses of at least half the warriors.
With the secret of the mist present in the world, the Khan was soon found assaulted by trade agreements to export the mist so that sick heads of state could be healed, ailments could be banished, and armies could be made invincible. The Khan agreed and tried to meet teh demands, but the mist’s wonders proved unable to be bottled. It simply stopped working within a day of leaving the valley. The Khan was soon met with the very emmisaries who had come bearing gift to gain his favor, but this time they bore declarations of war and labeled him a thief and a liar, and blamed for the death of a sickly heir.
With a valley of warriors at his command, the Khan set up defenses to hold the many armies at bay. Nations who were bitter rivals joined in greed as they descended on the small valley. The soilders who survived came back shaken, telling tales of invicible warriors leaping from the mist to strike fatal blows. The Khan denouced the nations that attacked him as evil and set up the permanent watch of his borders known to this day as the Line of Bone.
The Line of Bone is two hundred foot wide path of scattered bones and powder. The line marks the edges of the valley’s mist and it’s healing properties. The warriors that walk the line were given the name "Cloud walkers" because the bone powder puffs around their feet as they walk and often follows them on the soles of their shoes as they travel inside the valley. The Cloud walkers question anyone found on the line and have permission to slay them on sight.
It is unknown what gives the mist it’s healing properties, perhaps a mixing of exotic elements from the depths of the earth with rare moss spores, but all those who breathe it heal with remarkable speed. All those that have breathed the mists for at least one day may recover 2d4 hit points a combat round. After an day outside the mists, the healing powers stop.
The mist is not a heavy fog, but visibility inside the mist during the day is about a hundred feet, which is why the Line of Bone is two hundred feet wide, so they can see any invaders while remaining inside the mist. At night visibility drops to about twenty feet.
Many of the warriors have dogs with them. These "Mist Hounds" have been trained to attack with great ferocity to accomplish the kills neccesary in the mist.