It felt kind of obvious to me that it was an area in Prehistoric times you get warped to after fighting Magus, especially since the weird wind-blowing sound is used for Crono's dream and the area was programmed in that time. Perhaps they'd have made it the same place Ayla found Kino as an infant so that little bit of exposition would be more blatant (yes, Ayla raised Kino, it's just dialog that's out of the way to get).
Although the idea of it being used for Magus wandering around 12,000 BC is awesome, it would really spoil a lot too early...