Magic began to disappear and the dimensional rifts had closed, trapping beings and creatures not of this world on Earth and endangering Lemurian civilization which was reliant on magic. When the Atlantean cataclysm occurred, killing most of the Atlanteans, scattering the remnants across the Megaverse, and causing the disappearance of Atlantis itself, the Lemurians too suffered but in a different way. Unlike the Atlanteans whose civilization was based on an island continent in the north Atlantic Ocean, the Lemurian civilization decided to build mobile 'floating' cities.
Where the Atlanteans focused their scientific efforts on exploring other dimensions, the Lemurians focused their's on learning the secrets of the natural world.
They were contemporaries of the Atlanteans and in their own way their equals in science, magic, and technology. Lemurian civilization is 10,000s of thousands of years old.