Threave Castle stands on an island in the middle of the River Dee. During the mediaeval period the water level was higher and the island was only about a third of the size that it is today. Legend tells that Threave Island was the home of the ancient rulers of Galloway, but there is no physical proof of this. Archaeological evidence does seem to suggest that there was an earlier castle on the site, which by tradition was the residence of Fergus, Lord of Galloway, and his descendants from the mid 11th century onwards, and was probably destroyed by Robert the Bruce in 1308.