Dustwallow Marsh was once a high plain filled with herd animals that thrived on the tall grasses. Then came the great Sundering, and the plain was smashed down into a depressed valley. The water table bled up and saturated the landscape, creating the great marsh that exists today.
Dustwallow Marsh had long been home only to wild beasts, but all this changed in the Third War, when Jaina Proudmoore led her people here to settle down after the battle with Archimonde at Mount Hyjal. Founding the city of Theramore, Jaina's humans rapidly extended into the swamp, building fortified guard towers at important points along the road to the Barrens.
The ogres of Stonemaul, having settled in the region after Thrall brought a regiment of them to Kalimdor with his fleet, were called to war upon the humans by their newly established leader Rexxar, in response to an attack by Admiral Proudmoore and his Kul Tiras Marines. Dustwallow Marsh saw a great skirmish between the opposing forces, leading to the death of the zealous, albeit misguided hero of the Alliance.
In the south of the marsh, the black dragonflight has established a presence. Consequently, these regions of the swamp have come to be known as the Dragonmurk and the Wyrmbog. Until recently, the Stonemaul ogres lived in Stonemaul Village in this region in relative peace. The Mok'Nathal Rexxar assumed leadership of their tribe some time ago and forged an alliance between the Stonemaul and the Horde. The Black Dragonspawn attacked the village in a terrible rout and the surviving Stonemaul ogres were forced to retreat to Brackenwall. They have sworn revenge on the usurpers. It is said that this wilderness is also home to Onyxia, a great dragon and the daughter of Deathwing, although few adventurers have ever ventured into her lair and lived to tell the tale.