The Expedition Map represents the explorable area of each expedition. Map sections are split into relevant regions, which are represented as large highlighted squares on your map. As these areas are explored, their terrain and locations are revealed and applicable Exploration Points are awarded. The player is not required to uncover a full map in order to advance to the next expedition, and it's not uncommon to find the Golden Pyramid before some regions have even been discovered. However, Expeditions 4-6 tend to require more exploration in order to obtain the required moon stones or seals to unlock the pyramid.
Expedition maps become larger as the game progresses:
Darker regions on these maps never contain locations (with the exception of some Kill the Monsters quest spawns). Darker regions are generally blocked off with mountains, lakes, and forests. When the player reveals an impassable region, the map will trigger a banner stating this. Crossing a border into an impassable region does not award exploration points.
It's not uncommon for much of the relevant map to also be impassable. Sometimes nearly entire regions of the map are covered in water or mountains, forcing the party to take a specific route to reach the rest of the map.