Merlin couldn't have attended Hogwarts

The throwaway lines about Merlin being a Syltherin, the reference to a young Merlin in the Bell Tower quest, etc have been bothering me for a while and now I know why.

Hogwarts was founded in 1000 AD.

"Merlin" the mythical figure was alive during the time of King Arthur, in the 5th or 6th century!

The game writers' mistake: the stories about Merlin were created during the 12th century in the Medieval version of historical fiction!