The Mystara Setting
In 1999 Bruce Heard posted some old files on the Mystara Mailing List to help in the definition of the past of Mystara looking towards its future at the timing of the release of the third edition. The information presented in the Reference Guide and in Mystara - Before and After are presented as is, with the former having some comments added by Bruce. Some of the elements are no longer viable or factual given subsequent releases.
Reference Guide to Mystara from within TSR dated June 1991.
Mystara - Before and After is a file from within TSR dated '93-'94. This document was supposed to be part of a small "Guide to Mystara" to be used within TSR.
A Squid's Eye-View of Mystara is a copy of Polyhedron article designed to help introduce new people to Mystara.
Talking 3E for Mystara are updated Guidelines for 3E Mystara Project, a compilation of present thoughts by Bruce Heard from the Mystara Mailing List posted 27 October 1999. It contains thoughts on helping to present Mystara as a coherent game world in a manner that new players (and hopefully WotC staff) can see and take part in. The file also grabs together some thoughts for what makes Mystara a world worth playing in.