In 3500BC, Egyptians conceptualized that the beginning was a dark (no sun) watery abyss, modeled on the conjecture that world originally was “all water”, i.e. the earth was completely flooded, based on the annual Nile Rive flood, which yearly was seen to submerge entire islands, 30 to 40 in water rise:
In 2600BC, Egyptians defined the beginning or start of “creation” via several different scenarios: Nun or Ogdoad, both mixed with Maat and Thoth (and parts of Ra, in some versions); as outlined below:
In this model, the Egyptian Nun or Ogdoad, the god personification of the beginning, as watery abyss, void, emptiness, chaos, or space, existed first, out of which land arose (god: Atum), out of the tip of which the sun god (god: Ra) was born, from which all the other gods were engendered, namely: air (god: Shu) and Tefnut (moisture); earth (god: Geb) and sky (god: Nut); then Osiris, Isis, Set, and Nephthys.
In 750BC, Hesiod, in his Theogony, after studying in Egypt, presented a model of Greek cosmology, wherein the gods were generated from “chaos”, which basically was a rescript of the Egyptian void, vacuum, darkness aspects of the “Ogdoad” god family.
In 520BC, Pythagoras renamed Hesiod’s “chaos” by the number-themed word “monad”.
In 300BC, Epicurus, unhappy with his teacher’s inability to explain the meaning of “chaos” to him, turned to the atomic theories of Democritus, wherein he found solace.
The following are quotes:
- “In the beginning was chaos.”
- — Isiodos (c.850BC), Publication 
- Barry, Kieren. (1999). The Greek Qabalah: Alphabetic Mysticism and Numerology in the Ancient World (pdf) (theos, pg. 74; #284, pg. 227; #318, pg. 228; #345 (void; empty), pg. 229). Weiser.
- Hesiod. (750BC). Theogony (editor: Richmond Lattimore) (god genealogy table, pgs. 222-26). University of Michigan Press.
- Michaelides, Efstathios. (2006). Particles, Bubbles, and Drops: Their Motion, Heat, and Mass Transfer (pg. 1). World Scientific.
- Chaos – Hmolpedia 2020.