The primal ban is one names for an old, deep magic upheld by the collective primal spirits of the mortal world, that makes the world resist intrusion by mightier elemental and astral beings. The ban is embodied in the existential barriers that surround the natural world and wall out all other planes. Manifested during the last days of the Dawn War, the primal ban was the primal spirits way of deciding that gods and primordials both were to be denied direct influence in the natural world; they could influence it indirectly, but not rule it.
Some scholars assert that the primal spirits crafted the ban to guard their newborn world from the ravages of the Dawn War. Others believe that the laws of the natural world governing seasons, weather, and life that are ingrained in the primal spirits came to develop an inherent strength of their own that resists the caprices of god and primordial both.
The primal ban is not absolute, nor is it impervious. The most powerful primordiaIs and gods can resist or defy its effects with great effort. Many lesser elemental powers can do so in places where elemental influence is naturally strong in the world, or when the proper conditions lend them the strength to act. However, the surest way to circumvent the ban is to work through mortal creatures. The warding does not constrain the acts of creatures native to the natural world, so mortals who call upon divine aid or elemental energy can bring these forces into the world much more easily than gods or primordiaIs can make their way in from outside.