This is a question I've been concerned about in my world for a while now. There are multiple stopping points I can take for that to be the end of my lore-building, but I'm not sure which one I should go for. Obviously, my lore doesn't reach all the way back to the dawn of time, have to keep a bit of mystery going ya know. But I've been curious about how other people view this dilemma.
So, I'm opening up this question to everyone to answer. How far back should lore go? Is it dependent on the story, or is there a set average? How do you know you've gone too far? Alternatively, how do you know when you don't have enough?