Thuria was, during the Pre-Cataclysmic Age, one of the Earth largest land masses although smaller continents such as Atlantis and the eastern continent of Mu existed, as did several island chains. Most of the Earth was unexplored wilderness but contained scattered clans of primitive humans.
One of the nations to exist at the time was Valusia, with its capital the City of Wonders, ruled by King Kull.
In 18,000 B.C. Atlantis sank beneath the ocean during what is known as the Great Cataclysm. This event changed the landscape of the world, which would be known as Hyboria.