We've mentioned earlier that several items for sale at the Treno Auction House are from previous FINAL FANTASY titles. There is some purpose to this.

After returning to Gaia from Terra, purchase Doga's Artifact and Une's Mirror from the auction and return to the Black Mage Village. Speak to the Black Mage standing in front of the phonograph inside the Inn. This causes the background music to change to a tune from FINAL FANTASY III's soundtrack. This special music continues until you leave the village.