Era beginning/end
The beings of power came together and decided to cease their direct wars with each other, and instead create the known worlds, and the races upon them to suit their whims.
At the end of The First Eon, the gods and beings of power realized that their wars with each other destroyed countless worlds, life, and universes that they rebuilt, only to destroy again. They resolved that they would no longer directly assault each other, and created the known worlds and planes, then created the various races and beings who would reside upon them. After breathing life into their creations, the beings of power watched over them, and used them in their fights against one another; the might of mortals could do great damage, but never again the destruction of universes.