The Praxians were the first advanced human civilization on Earth. They were related in some way to the Sumerian civilization that arose in Mesopotamia, though it is not clear whether the Praxians were an offshoot of the Sumerians or vice versa.
They and many abnormals fought a great war against the Akhkharu (vampires), who eventually defeated them and drove them underground. While the vampires were defeated by internal struggles and the rise of the second, current iteration of humanity on the surface, the Praxians settled in Hollow Earth and built the great city of Praxis. Throughout the thousands of years of their history, the Praxians retained cuneiform as their written language.