From the introduction:
Centuries ago, the old civilization ended. Nobody remembers how or why, but the worldwide empire of humanity broke, their technologies were forgotten and fell out of use, their cities crumbled. The only thing that endured, are their stories.
Most of them have been lost but some still remain, kept safe in the Hollowed Halls, the great library of the Lost Stories. While the remaining humans spread out and formed tribes, small communities of only a few hundred people each, these stories were all they could hold on to.
Stories are what guides them, shows them how to act and how to succeed in the world.