590 A.D.

Lavos Timeline

-Queen Leene marries into the Guardia royal family.
-Cyrus and Glenn recover a medal, the Badge of Courage, from the Frog King. 
-Cyrus obtains the Masamune.
-Magus breaks the Masamune in a fight with Cyrus and Glenn. 
-Cyrus is murdered by Magus and Ozzie; Glenn becomes Frog by Magus' spell. 
-A beast is seen carrying something into the Northern Ruins, where Cyrus is 
buried. This is most likely Frog burying Cyrus.
-Cyrus's ghost cannot be helped, and haunts the ruins.

Keystone T-1

-Queen Leene marries into the Guardia royal family.
-Cyrus and Glenn recover a medal, the Badge of Courage, from the Frog King. 
-Cyrus obtains the Masamune.
-Magus breaks the Masamune in a fight with Cyrus and Glenn. 
-Cyrus is murdered by Magus and Ozzie; Glenn becomes Frog by Magus' spell. 
-A beast is seen carrying something into the Northern Ruins, where Cyrus is 
buried. This is most likely Frog burying Cyrus.
-Cyrus's ghost cannot be helped, and haunts the ruins.

Keystone T-2

-Queen Leene marries into the Guardia royal family.
-Cyrus and Glenn recover a medal, the Badge of Courage, from the Frog King. 
-Cyrus obtains the Masamune.
-Magus breaks the Masamune in a fight with Cyrus and Glenn. 
-Cyrus is murdered by Magus and Ozzie; Glenn becomes Frog by Magus' spell. 
-A beast is seen carrying something into the Northern Ruins, where Cyrus is 
buried. This is most likely Frog burying Cyrus.
-Cyrus's ghost cannot be helped, and haunts the ruins.

From: Chronology