On the history itself: I liked it. It reads like an account of a series of migrations, which feels accurate to the setting feel. More specifically:

  1. You could use a timeline to keep everything straight.
  2. Your creation story feels a little disjointed and sanitized. Reading some of the early creation stories reveals the gods weren't averse to use anything to make the world. Even some questionable usage of certain liquids in the human body.
  3. As you said in my thread, Gods of this era are capricious. I'd like to see some examples of cruelty by the gods as well as some kindness (see: Ishtar in the Epic of Gilgamesh). At their worst, Mesopotamian gods were pitiless Cthulhu like monsters. To quote TV Tropes:
    Crapsack World: Humans were created to be slaves to the gods and when they died, they all went to the same gloomy underworld. Any wonder why their scribes wrote stuff like this:
    "Tears, lament, anguish, and depression are within me. Suffering overwhelms me. Evil fate holds me and carries off my life. Malignant sickness bathes me."
  4. I do believe that ancient Sumerians, or ancient folk in general, would call a Dragon a Serpent. Great Wyrm also works, but the word Dragon itself doesn't sit well with me.
  5. In your history, you have a lot of conflict between shepherds and farmers. According to historian Robert L O'Connell, the very first wars would have been fought between these two forces. So Kudos!
  6. So, let me know if I'm reading this right. The Sabylians read an awful lot like Hittites, what with their animal husbandry and horsemanship (I would suggest having them invent chariots!). The Vabbians are the Indo-European, or Aryan invaders (they have iron and they displace and conquer everyone else). The Tamazians look like native Sumerians. The Sinatic people are Israelites, and the Aserians are essentially Babylon (except they built a dragon instead of a tower, so sweet). Did I get that right?