After a request for an idea of the size and placement of the empires spoken of in the histories, I did an overlay on the Before and After maps from History 07: The Sealing of the World, Part 2 to show their former areas.  See below:

Though ugly, this shows the territory claimed by each empire (labeled in red) just before the Seals were completed.  Ruen Wyn is a patchwork of colors because at this time it is not a complete empire, but rather a cluster of small warring kingdoms.

Using the same colored overlay from the previous map, this After-Sealing map shows both the reduced spread of the empires and the amount of lost land.