The Schism

After The Creation of the Material Planes, all of the living beings of Vylderaine were living on a single massive continent. Nobody knows how long this Age of Creation lasted, but it assumed centuries. At first everything on Vylderaine was great, for the most part everyone got along, technology and culture were advancing, and everyone had their space. But eventually all these things came to an end. When the material planes were first created the deities did not plan on the Primordials populating them. Aedifidea - Planar Architect and Tempmet - Time's Arrow / Moons' Keeper planned on bringing some of their subjects from Pinnacle to the Material Plane to begin populating it. But after the sundering of the primordials in the creation this plan was abandoned. One unforseen consequence of this occurring was that primordials were by their nature, immortal, and because of this so were their fragments.
After centuries of the immortal beings born of the sundering of the primordials living on the material planes, the vast majority of which were on the main Material Plane, space and resources began to grow scare on the continent. This led to malcontent amongst the residents of the Material Plane, and with influence from more of the nefarious deities such as Khuvala - Matron of Many Faces / Mistress of the Hells, Rājad - Emperor in Gold / King of the Demon Lords, and Ükhelzen - Deathbringer / Harbinger of Mortality violence and wars began to erupt over the lack of resources. The violence brought upon the multitudes of beings who were incapable of dying led to untold suffering and because all of the deities had agreed to only influence the material planes from afar, there was nothing to be done. Until Ashephine - Mother of All Endings / Ashen Mother arrived.
Ashephine is a deific being from The Void who took pity on the beings of the Material Plane and arrived physically on the plane to bring with her her negative energies from her own domain to bring death and relief to those suffering. Everyone who was living in constant pain and suffering painlessly turned to ash and died, while everyone else was given an ultimatum from Ashephine: any who bring violence or suffering upon another shall from there on end not only their own immortality but also the immortality of all like them. For years a tentative peace befell the residents of the Material Plane as they witnessed death for the first time. However, once the other deities involved in the creation of the material planes learned of Ashephine's direct involvement in the plane's affairs their pact was broken.
The deities descended upon the material planes to try and exert their own influences more forcefully. Armies were formed under the deities names and war broke out among many of the ancestries of the material plane. Many mananged to avoid the death and violence for as long as they could, while many gave in almost immediately. Goblins for example were quick to pick up arms against the other ancestries only 25 years after the ultimatum given by Ashepine, as a result all goblins older than 25 immediately turned to ash and died and all future goblins had an approximate max lifespan of 25. On the other end of the spectrum were dwarves and elves who managed to last around 200 and 300 years respectively by hiding from the violence underground or by adopting pacifisim. In the end though, all ancestries became mortal and the gods ended up carving up the continent of Vylderaine into many smaller continents.
This violence continued for many years until the celestial goddess Hemarra - Sanguine Queen / Scarlet Martyr made a deal with the infernal goddess Khuvala - Matron of Many Faces / Mistress of the Hells. Hemarra promised her physical, beating heart to Khuvala and in return Khuvala would take her devilsh forces and return to Hell and take the demons and daemons with them, trapping them back in The Abyss and Abaddon respectively. Khuvala, eager to have power over a celestial goddess, accepted the offer and retreated back to the infernal planes with Hemarra's heart along with the other infernal deities and subjects. With the absence of infernal presence on the Material Plane the celestial deities retreated back to their own planes along with the rest of Hemarra's body, still alive, even without a heart, but locked in an eternal slumber. Without the war of the celestials and infernals taking place on the Material Plane the other deities retreated back to their own domains as well and another tentative peace returned to the Material Plane that still lasts to this age...