In the beginning, the world was unformed and stagnant. Dragons existed in a state that was neither life nor death, ruling a world shrouded in fog, neither light nor dark, neither warm nor cold. Then came the Fire that changed everything, bringing chaos to the stagnant order: heat and cold, life and death, Light and Dark.
From the Dark came those who found the Souls of Lords within the Fire, becoming the rulers of this disparity. Nito, the first of the dead; the Witch of Izalith, creator of pyromancy; Gwyn, the Lord of Sunlight, and his loyal knights; and the pygmy, possessor of the ominous Dark Soul. With their powers, the Lords overcame the dragons, ushering in their own Age. The Age of Fire saw prosperity as the Lords established themselves in Lordran and formed their separate, yet equal kingdoms, the most brilliant of them being Gwyn's city of Anor Londo.
But the signs of turmoil are starting to show themselves. The Fire is fading, and Gwyn has left his charges to attempt to rekindle the flames, a doomed attempt at returning Light to the world. The Darkwraiths, minions of the dark Abyss, have crawled up to consume the souls and humanity of those above, barely held back by the efforts of Sir Artorias the Abysswalker. The strength of the Lords is weakening, and it seems to only be a matter of time before Age of Fire dies with a flickering whimper.