The Divine Calamity

In the Beginning
When the planes were created, no one knows who originated it. All we know was the main creator god split their body apart and sacrificed their essence to create the gods, pouring their soul into the material plane. The remains of this god can be found in the form of Ketvia crystals, named after the scholar who discovered them.

The gods, both good evil chaotic and lawful, all began to build upon the existing blank planes. Pelor and Makar grew to be the two most prominent of the gods, each of them brothers born of the same piece of the creator god, rumored to be the heart. When the mortal races were created, Makar and his followers retorted by creating demons and devils and all things evil, and Pelor created the celestials and elementals. Within this whole hot mess arose the Primordials, created by either side on accident in their quest to create new life. Progress would continue, as would competition. However, it all came crashing down when Makar decided his brother and his followers should not have say over this multiverse.

The Calamity
Makar and Pelor's conflict grew and grew until war finally broke out. The two opposing sides became known later as the Protector and Betrayer Gods, with the Primordials choosing sides as they saw fit. The mortal races and celestials fought against the hordes of evil that crashed down upon them. The fighting reached a stalemate until Asmodeus offered a way out to Pelor. Asmodeus knew of Moradin's plan to forge the Divine Gate and keep all gods in their own planes forever and outside the material plane, but wanted to have more influence on the plane. So, he offered to chain and lock up Makar while he was distracted fighting Pelor and his followers. Pelor agreed, seeking an end to his brother's tyranny. So Pelor, Bahamut, and Pan all ambushed Makar to distract him. Asmodeus chained and shackled him while he was fighting, then dragged him down to the bottom layer of the Nine Hells for good. Seeing the war was over, all the Betrayer gods returned to their own planes to avoid Pelor's now much more open wrath that was once diverted by his brother but no longer. Moradin finished the Divine Gate and the gods have remained outside the material plane and inside their own planes ever since.

Several of these deities and beings who fought in the war remained unaccounted for, believed to be hiding somewhere in the material plane amassing power or really just doing whatever they want. The Primordials remain rather present, despite the fact most of them were killed or thought to be dead. Krakens are the most famous example and most prevalent, with species like the Tarrasque believing to have gone extinct.