(Source: Vulgate Cycle - Lancelot pt. III)
The Land of Gorre, home of Sir Maleagant and King Bagdemagus, as described in the Prose Lancelot.
Due to the French Romances establishing the idea that King Urien was Bagdemagus' uncle and left Gorre to him, many writers have come to identify Gorre with the historical Kingdom of Rheged in Southern Scotland.
However, I hold a certain level of skepticism regarding this. Not accounting for the fact that the real historical Urien of Rheged actually reigned AFTER the purported era of King Arthur, there's also the fact that beyond the French Prose Cycles, there is no earlier evidence to support Uriens having a familial connection with Bagdemagus and Maleagant. How the Gorre family became kinsmen of Uriens in the evolution of the legends is still a mystery.
In fact, the description of Gorre above - with it bordering North Wales and enclosed on all sides with significant bodies of water - cannot physically match any area in the "Old North". Instead, it strikingly resembles a description of Anglesey (otherwise known as Ynys Mon):
If so, this is also very curious because in earlier sources, the original version of Sir Meleagant, Melwas, was called the King of the "Summer Country" to which many a scholar have identified as Somerset and his chief stronghold - where he imprisoned Guinevere - was Glastonbury.
