12000 B.C. to 1 A.D.
From Chrono Compendium
Lavos Timeline
-The land warms up. *The blue pyramid, which stores Zeal's mightiest weapons, surfaces in a forest. It is not accessible to Crono's party until 1000 A.D. *Many sealed treasure boxes from Zeal scatter throughout the land. *Schala's pendant finds its way to the Earthbound, and is passed along the Guardia line. *The Masamune is sealed in a cave in the Denadoro mountains.
Keystone T-1
-The land warms up. *The blue pyramid, which stores Zeal's mightiest weapons, surfaces in a forest. It is not accessible to Crono's party until 1000 A.D. *Many sealed treasure boxes from Zeal scatter throughout the land. *Schala's pendant finds its way to the Earthbound, and is passed along the Guardia line. *The Masamune is sealed in a cave in the Denadoro mountains.
Keystone T-2
-The land warms up. *The blue pyramid, which stores Zeal's mightiest weapons, surfaces in a forest. It is not accessible to Crono's party until 1000 A.D. *Many sealed treasure boxes from Zeal scatter throughout the land. *Schala's pendant finds its way to the Earthbound, and is passed along the Guardia line. *The Masamune is sealed in a cave in the Denadoro mountains.
From: Chronology