The Drunken Lizard Pub

Edit: So I fought sleep, downloaded the map editor, and managed to create a 5052.map and traveled to it, whereas the game previously told me there was nothing there and to turn back. YUSSS!!! It appears creating new exterior locations is possible.

You are indeed correct, I have utilised this in ...

So I've been looking at the names of the maps in my saves folder and it looks like the maps are named based on their x / y coordinates on the world grid.

For example, the tile / area you start in at the beginning of the game (eastwillow / Yoma River Valley) is 5050.map, while Port Kuudad is 2 ...