Allow me to give you an idea of how big my fantasy world is in Numen the Slayer. The nine kingdoms of the Empire are the same size as all the combined territory of the British Empire at its zenith. The red on this map is the British Empire’s territory at its peak so if you combine all that land then you will get the Empire of Gradaia. However, it is the only landmass in this entire fantasy world and everything else is open ocean. Due to this whoever controls the Empire literally controls the world.