Deep Dwarf Rush
Due to current seafaring technology, no civilization from either continent can currently make long-range exploratory journeys. Even the southern reaches of Southworld are unknown as no ship has ever come back from the treacherous coastal waters on either side of the vast continent.
These lands are seldom referred to as the Known World by common people. Scholars interested in geography and history will often refer to it thus to distinguish between Jhai the planet and the part of it that they know is there.