Plains of Denaria

The Plains of Denaria are a wasteland characterized by a rocky, dusty and barren landscape. It's unknown in which part of the land of Albion the Plains are located, but it's likely that they are somewhere between the city of Camelot, or The Valley of the Fallen Kings (for Morgana's hut, where she took care of Morgause it's likely to be there) and the Isle of the Blessed.

When war broke out between Uther and Carleon, their armies met and fought on the Plains of Denaria the battle that is now called the Battle of Denaria. When Carleon was about to be defeated, he retreated to the Castle of Fyrien. This indicates that the Plains are also near the Castle of Fyrien and so near The Great Seas of Meredor (this is very likely, for the Isle of the Blessed is near the Seas of Meredor) (The Castle of Fyrien).

Sir Leon, Sir Elyan, Sir Bertrand and Sir Montague caught up with Morgana on the Plains of Denaria when she was taking her sister to the Isle of the Blessed. When they approached her, she used Stunning Spells to knock them out. While Elyan and Leon survived, Sir Bertrand and Sir Montague died (The Darkest Hour).