This "mixing of the waters" Harriet Crawford finds to be a natural feature of the middle Persian Gulf, where fresh waters from the Arabian aquifer mix and mingle with the salt waters of the sea. This characteristic is especially true of the region of Bahrain, whose name means in Arabic, "two seas" and which is thought to be the site of Dilmun, the original site of the Sumerian creation.
Though Tiamat is often described by modern authors as a sea serpent or dragon, no ancient texts exist in which there is a clear association with those kinds of creatures. Though the Enûma Elish specifically states that Tiamat did give birth to dragons and serpents, they are included among a larger and more general list of monsters including scorpion men and merpeople, none of which imply that any of the children resemble the mother or are even limited to aquatic creatures.
The depiction of Tiamat as a multi-headed dragon was popularized in the 1970s as a fixture of the Dungeons & Dragons roleplaying game. This image selects one rendition of Tiamat's form from among many, including ancient artistic depictions of her as a single-headed dragon and a serpent.
Apsu (or Abzu, from Sumerian ab = water, zu = far) fathered upon Tiamat the Elder Gods Lahmu and Lahamu (the "muddy"), a title given to the gatekeepers at the Enki Abzu temple in Eridu. Lahmu and Lahamu, in turn, were the parents of the axis or pivot of the heavens (Anshar, from an = heaven, shar = axle or pivot) and the earth (Kishar); Anshar and Kishar were considered to meet on the horizon, becoming thereby the parents of Anu and Ki. Tiamat was the "shining" personification of salt water who roared and smote in the chaos of original creation. She and Apsu filled the cosmic abyss with the primeval waters. She is "Ummu-Hubur who formed all things".
In the myth recorded on cuneiform tablets, the god Enki (later Ea) believed correctly that Apsu, upset with the chaos they created, was planning to murder the younger gods; and so slew him. This angered Kingu, their son, who reported the event to Tiamat, whereupon she fashioned monsters to battle the gods in order to avenge Apsu's death. These were her own offspring: giant sea serpents, storm demons, fish-men, scorpion-men and many others. Tiamat possessed the Tablets of Destiny, and in the primordial battle she gave them to Kingu, the god she had chosen as her lover and the leader of her host. The Gods gathered in terror, but Anu, (replaced later, first by Enlil and, in the late version that has survived after the First Dynasty of Babylon, by Marduk, the son of Ea), first extracting a promise that he would be revered as "king of the gods", overcame her, armed with the arrows of the winds, a net, a club, and an invincible spear.
Slicing Tiamat in half, he made from her ribs the vault of heaven and earth. Her weeping eyes became the source of the Tigris and the Euphrates. With the approval of the elder gods, he took from Kingu the Tablets of Destiny, installing himself as the head of the Babylonian pantheon. Kingu was captured and was later slain: his red blood mixed with the red clay of the Earth would make the body of humankind, created to act as the servant of the younger Igigi Gods.
The principal theme of the epic is the justified elevation of Marduk to command over all the gods. "It has long been realized that the Marduk epic, for all its local coloring and probable elaboration by the Babylonian theologians, reflects in substance older Sumerian material," E. A. Speiser remarked in 1942 adding "The exact Sumerian prototype, however, has not turned up so far." Without corroboration in surviving texts, this surmise that the Babylonian version of the story is based upon a modified version of an older epic, in which Enlil, not Marduk, was the god who slew Tiamat, is more recently dismissed as "distinctly improbable", Marduk in fact has no precise Sumerian prototype.