I've been DMing a 2nd Ed. AD&D Mystara Campaing for a while, but the more I read about the lore of the old suplements from the setting (basic D&D), the more I think the timeline in the 2nd Ed. books are not the same canon as the classic gazetter line of the Known World. Are they separate timelines?
The timeline in the 2nd Ed. books starts in the year 1012DC, where many things are different from de Basic D&D timeline (which starts in the year 1000DC) — things like the fact the The Grand Duchy of Karameikos is already a independent Kingdom, the entire Empire of Aplhatia has sunk into the ocean, and many other minor changes.
My problem is that these changes are only stated in the 2nd Ed. AD&D Mystara line of books, and BECMI D&D sites like the Vaults of Pandius have kept progressing the lore in the 1000DC timeline. Is each world its own canon timeline?