First appears in: The Death Edge
Supe Valley is an ancient geographic region in Peru on Earth, serving as the setting for the story of the first Prime Mages. Kythaela recounts a mentorfire tale that "takes place over five thousand years ago, near a city which would soon be called Caral, in the Supe Valley, in Peru". The valley was home to early elven settlements, including the triplets Usunaar, Talanaar, and Koranaar, who were "unique in recorded history".
The region became a battleground when "a band of warrior Kotosh swept in from the coast south of the Supe Valley, intent on death and destruction". This conflict in the valley ultimately led to the emergence of the first Prime Mages, the ancient Sundering, and the birth of the twin Prime Trees when Talanaar's tears fell in the nearby Queñua forest.