While World Map is the most helpful tool for the DM to design their overarching sandbox campaign, Region Maps is one of the most valuable tools for the player to experience your story in your Sandbox Campaigns. Regional Maps entice the players to go to different plot hooks and be intrigued by what the region offers. For the DM, it's also a valuable tool for planning your quests and having a player progression that does not go out of hand with too many choices for your players but also provides the freedom to explore your sandbox campaign organically.