Once you get the epoch, you can go AROUND the freeking planet! And yet even if you go around the planet there is no sign of Fort Dragonia or a majority of 1020s locations.
Unfortunately, you can't go somewhere that doesn't exist yet. As the point others made, El Nido was created after the events of CT. Unfortunately after the events of CT, we never really get to see what the map has turned into.
But surely the geological and political changes that happen between the two games would've taken much more than 20 years.
In a sense, all of those changes took much more than 20 years.
About 10,000 years due to Chronopolis coming into existence. Now mind you, in the 20 years (besides Porre having a huge change), I guess right now, we can say that the map of the main continent didn't really undergo any major changes compared to what we saw. Of course, we don't really know this being that in CC, we didn't ever get to see the main continent.
Why is it that all of a sudden all of the kingdoms in CT are gone and there are so many new ones? Also, isn't Fort Dragonia supposed to be really old? Where is it in CT? So much global developement and geological change would take much longer than 20 years.
None of the kingdoms in CT are gone (unless Guardia was smashed to the ground and Radius is only referring to them in the past tense). El Nido is just a different (and new) subsection of the Chrono world. Otherwise, where would Porre go if that area didn't exist in CC?
As Doc refers to the dangerous tides of El Nido, the waterflow in the Northwest of the El Nido map appears that it could be the only exit out of that section of the map. Of course, being that your party never has access to a large vessel, you can't leave El Nido obviously. However, the Porre military can come and go from El Nido at will as they obviously do have the benefit of a large vessel.
So my theory (for now at least) is that the maps of CT and CC are one on top of the other. That layout will also back up the statement of Porre being "The major power to the east." Technically, it would be northeast, but still nonetheless, east.
As far as Fort Dragonia, as stated above, it didn't exist yet during CT so of course you can't go there in that game.
