Location from Solo Leveling by Chugong
The dimension where the Monarchs originate — a world of darkness and power that bleeds into Earth through Gates.
The Monarchs' Realm is the dimension where the Monarchs and their armies exist. It's a world antithetical to human existence — a dimension of raw magical power, darkness, and ancient beings that have been waging war since before human civilization. The Monarchs use Gates to breach the barrier between their realm and Earth, sending monsters through as advance forces before attempting full-scale invasion. The realm itself is hostile to human life; only beings empowered by the System, Rulers, or Monarchs can survive there.
Also known as: Monarchs' Realm, The Monarchs' Dimension, The Other Side