People! They mostly live in Human States. Humanity is the most widespread race of the Warhammer world.
When the civilization of the Old Ones fell, humans were still a new experiment. They were among the last creations of the Old Ones, and presumably the development of the human race was left incomplete, leaving it as a whole susceptible to the influences of Chaos.
At the time of collapse of the warp gates, the ancestors of humans were living in the equatorial regions of the world. They existed in the most primal state, barely above the level of apes. Undeveloped culturally, the humans were the most vulnerable of the creations of the Old Ones to the Chaos dust which rained down on the world. The most far reaching effects were the acceleration of physical and cultural progress, and the shaping of the human mind.
Unlike the elder races, humanity possessed a vigor and mental adaptability derived from Chaos. Humanity grew swiftly and strongly, in time surpassing the elder races.
Humans are organized in several competing states, nations, and tribes. They inhabit nearly all regions from the Old World to Araby and to the far eastern Cathay and Nippon. Humans are also the favoured tools of the Gods of Chaos and many brutal tribes roam the northern Chaos Wastes.