The Royal Undergound Path was presumably built not long after the foundation of Dipan itself. The latter being an island kingdom, its citizens needed a safe escape route in case of war or siege. According to Dylan, who used to be a soldier of Dipan, the path was built at the cost of many lives, but it ultimately serves its purpose, allowing the citizens of Dipan to evacuate to the mainland after the events of Chapter 4. It was also used to discreetly convey Alicia out of the kingdom when she was a child.