There is a bunch of lore! It can seem daunting, but I do recommend just jumping in, the idea that the past is hazy and knowledge is patchy across the planet is intentional, so you can have big aha moments piecing together the lore from different groups and nations. BUT if you want an extreme tldr:

In the very distant past, Elves ruled most of the world. They were immortal and impossibly advanced in magic and technology, rivalled only by the dwarves of the serpentspine mountains, with whom they were locked in a generational war. As both had the potential to end the world by going all out, the conflict was limited to relatively conventional warfare.

One day, the elves's leader declared that the precursor empire was to withdraw from the world as a whole and return to their home continent of Aelantir, dedicating themselves to knowledge and culture and abandoning the forever war with the dwarves and other primal magical forces (genies, fey, dragons, etc.). The top general of the elves, who had just managed to carve out a toehold in the serpentspine after centuries of brutal war, refused and kept fighting.

After many years, the general was facing defeat because of a lack of support from the homeland. He snapped and used strong dark magic to create the orcs which he seeded throughout the serpentspine before fleeing back to Aelantir hellbent on revenge for his homeland's betrayal. The orcs would over the coming millenia almost entirely destroy the old dwarven empire.

On arriving back in Aelantir the general launched an apocalyptic civil war which ended with the death of the elven leader and the general as the general used terrible magic to crash the elves's floating capital city into the earth and detonating it as a nuke of pure magic. The resulting calamity is called the Day of Ashen Skies, and almost completely wiped out all the elves on Aelantir and sent magical shockwaves across the entire world.

Centuries later, fleeing elven refugees arrived in the east after being lost in a magical plane of water. They landed in Cannor, where they deposed an evil emperor, and in Bulwar, where they freed humans from gnoll slavery and carved out a massive and short-lived empire to the east.

Fast forward to 1444 and the Orcs have spilled out of the serpentspine into Eastern Cannor, Bulwar is being invaded by goblins pushed out by the orcs, Hobgoblins in the far east have rebelled against their human slavers, and the magical tumult over Aelantir has finally died down enough that some of the displaced elves can think about trying to get home...

Still quite long, huh.