I'm playing as the Byzantine character, and after taking over the three towns close to me on the right side of the map, I can't seem to find any way to get to the rest of the map. The Lower Camp seems to almost have a bridge but it's not there (and info I've found suggests that it needs to be built from the other direction), and there don't seem to be any other teleporters in other regions that lead outside of this half of the map.

About the only one that show promise is on the 'Witchdoctor near Stream' map (actually the centaur); when I go out of that exit, I end up on a small map called 'Ness', and if I try to move more than a little away it automatically teleports me to where I came from. The other route I tried is to go into the cave the centaur's guarding, but even if I could survive the battles everything suggests that this is the final dungeon, and I don't have the full Dragon Amulet or all the necessary keys (just the Fire Key so far).

Am I missing something obvious? The one guide I found makes it sound like I could try a trick with an artifact that lets you view at a distance, but there must be some other way to progress than rely on that.

I found a possible solution, at least for moving across the map.

It turns out it is possible to advance by going into the centaur's cave. There's an alternate exit from there into the Moon Cave, and then you can exit into the Witchdoctor near Abyss, without having to fight anyone in the cave. From there I was able to use an orb to get back 'home'. I can now go back and forth (as long as I purchase two orbs or have enough money to get another one after jumping). I still don't know if that's an expected route, or if there's something weird about that Ness area, as I'm unable to find any mention of it in anyone else's posts on this game.