A visual compilation of the events before Undertale based on research from @nochocolate. Special thanks to the mods of NoChocolate for all the help and proofreading!
Not every event is captured on this timeline, but the main chronological order of events and the rare, specific mentions of dates are included. In order to be as objective as possible, theories and speculation have been omitted. All data has been taken at face value (including possible hyperbole, such as Bratty claiming they’ve been underground for “millennia”).
(Updated on April 4, 2016 to include Dogamy, Dogaressa, and Napstablook.)