One of the best things about Dark Souls is how it handles backstory — which is to say it buries it in the woods upstate and hopes you find it. That is why this (mostly) accurate explainer is so rewarding!
That's not to say it's intelligible, though! Dark Souls: In Summary by PlagueOfGripes takes the cryptic, esoteric backstory of Dark Souls and shows just how absurd, convoluted and oddly wonderful it is. Oh, plus it has Sif, The Great Grey Wolf appear as a tiny puppy. So there's that.