This may not necessarily be true since I am just speculating on the idea. Well, I was looking at a full map of 12,000 B.C. before the fall of Zeal Palace in Chrono Trigger. I had been glancing at a few maps just out of boredom. Anyway, an idea came into my head and so I thought more about it and began speculating. Before I tell you my theory, I wanted to point out some other things real quick.
You can fully explore the entire area of the Prehistoric Era, Middle Ages Era, Present Era, Future Era, and even the Dark Ages Era after the fall of Zeal Palace and the Ocean Palace incident, thanks to the Epoch. At the End of Time, the dwelling where Spekkio and Gaspar reside is the only place of residence at the End of Time while the rest of that existence is infinite darkness/blackness. In the Apocalyptic Era, anything that was worth exploring (if allowed to) ends up becoming ruins anyway, and in the Future, you get to explore what is left after three centuries of the occurrence of the Apocalypse. Also, any and all of Zeal Palace that could have been explored that wasn't, ends up sinking anyway and we all already pretty much know what was in the Sun Palace/Sun Keep and the Forbidden Palace/Northern Palace, or know a bit about them.
So, back to the map of the Dark Ages before the fall of Zeal Palace, during the Ice Age blizzard. We never really get to explore the entire area of this era since we do not have the Epoch and when we do receive the Epoch, it cannot fly due to the lack of wings. We also get to access all of the continents on foot except for the northern/northwestern continent.
With all of that said, let me now explain my theory.
I speculated that there was another possible Earthbound dwelling that existed on that northern/northwestern continent in the Dark Ages before the fall of Zeal Palace, during the Ice Age blizzard. We absolutely have no access to it whatsoever, it is never mentioned with the lack of significance to the storyline and such, and by the time that we would have had access to the said continent, it is already under the sea which means that if there was an Earthbound dwelling, it was wiped out.
This is really just a theory that I came up with, and I even gave it some more thought which lead me to the making of this long, thought out post. To be truthful, I came up with it earlier and am typing this down as I go and the ideas that are relevant to this theory.
I also figured that if there truly was, or ideally was, an Earthbound dwelling, it would most likely be in the mountain(s) or in a cave in the mountain(s) that leads underground. I am also aware that, if there was a dwelling here, then we should have had access to it, or else why bother? Well, this was just an idea that I was playing around with and wanted to see what you guys thought about it.
This is all I can think of for now. Tell me what you think, give me reasons why this is flawed, agree or disagree, etc etc.
I also wanted to know what your answer is to this question. Do you all think that there might have been another possible Earthbound dwelling in the northern/northwestern continent, in the Dark Ages before the fall of Zeal Palace, during the Ice Age blizzard?