500 B.D, In Outsiders term this happened two thousand years ago.
The gods weren't natives of the Empyrean. They were beings that travel through worlds and evolve themselves to fulfill their purpose. They were individuals of different worlds and their goals were still uncertain to this day.
And when they descended into the mortal world called Empyrean. The vastness and the collection of souls were abundant. The problem was there were six supreme beings that were ruling the world while the other higher existences were ruling over a faction of people that followed them.
The six supremes were known as incarnations of sins. They were the manifestation and the will of the beings on Empyrean. They were far weaker than the gods that infiltrated Empyrean. As a consequence, the gods vanquished them and sealed them in the underworld.