Era beginning/end
The Primal Dragons snuff out the last bastions of resistance, solidifying their rule over the entire world. They carve the land, and much of the sea up between them.
After millennia of fighting agents of Chaos, the Primal Dragons triumphed. No corner of Zoar had not been touched by the shadow of Dragon wings. Before they depart the world, they leave one directive to their offspring: Treasure the world. Let it not be stolen by outsiders. So, the children of the Primal Dragons divide the material world into spheres of influence, ruled by the eldest of them.