For Orphics, it was called the 'Womb of Darkness' from which the Cosmic Egg that contained the Universe emerged. It is sometimes conflated with 'Black Winged Night'.
The idea is also found in Mesopotamia and associated with Tiamat the 'Dragon' of Chaos, from whose dismembered body the world was formed.
Genesis refers to the earliest conditions of the Earth as "without form and void," a state similar to chaos.
Primal Chaos was sometimes said to be the true foundation of reality, particularly by philosophers such as Heraclitus and those trained in Orphic schools. It was the opposite of Platonism. It was also probably what Aristotle had in mind when he developed the concept of Prima Materia in his attempt to combine Platonism with the Presocraticism and Naturalism. It was a concept inherited by the theory of Alchemy.