That's a good question, yogc- I think there are clear hints at what the war was, such as the Somnus description, but I can't seem to recollect it being clearly stated. Yet all is indicative that the Shadow wars were the ones taking place during TRPG2.
As for the angle that im2smart4u brings in, that's also true- TSoG is meant to be quite stand-alone, with no need for prior knowledge of the Telepath Universe.