I read elsewhere on this thread and another poster mentioned Gilgamesh. This seems the most likely origin of the biblical flood story has become a common theme in Christianity. A story that most likely developed as an oral tradition about some catastrophic local or regional flood. It seemed like it enveloped the world to those that experienced it, because their world wasn't that big at the time in the sense of their perspective.
There are evidences that the Epic of Gilgamesh were popular and spread as far west as the Hittite empire in the north and Egypt in the south.
And since the Southern Levant - which Bronze Age Canaan, and Iron Age Israel and Judah - the region become hub and gateway, not only for wars and conquests, but also for trades and cultural exchanges.
Canaan, and the later Israel and Judah, were not isolated from neighbouring kingdoms or tribal nations.
The Epic of Gilgamesh were well known, during Bronze Age (mostly from mid to late 2 millennium BCE, so about 17th or 16th century to the start of 10th century BCE) and Iron Age.
Tablets, sometimes whole, but most of time fragmented and damaged, managed to survive complete destruction and loss, have been discovered with other Mesopotamian texts in these sites, outside of Babylonia (and Assyria).
For instances, during the mid-2nd millennium BCE, Middle Babylonian texts (during the Kassite empire), including the Epic of Gilgamesh, have found their ways to Mari, northern Syria, and even further north and west, in the Hittite capital, Hattsua.
And some tablets were found in religious capital of Akhenaten or Amenhotep IV (1353 - 1336 BCE, 18th dynasty, New Kingdom period) - Akhetaten, which is better known today as Amarna.
Fragments of the epic and other stories are found in many locations, including that of Ugarit and Megiddo, that are dated to the mid-2nd millennium BCE, hence the late Bronze Age.
These tablets are evidences that such a story predated the Genesis being composed during the Iron Age, 7th century BCE.
The Epic was still popular at the time of Genesis composition, where most of the extant collection of tablets (the epic of Gilgamesh, eleven tablets) were copied and kept in the Library of Ashurbanipal, Nineveh. The Library was discovered in the mid-19th century. This collection of 11 tablets became known as the Standard Version.
Even older version of the epic exist, tablets (fragments) kept at University Museum in Pennsylvania, and one fragment at Yale Babylonian Collection in New Haven, Connecticut.
An independent epic, known as the Epic of Atrahasis, was written in Old Babylonian, most likely dated to 17th century BCE. Atrahasis is mostly likely the original Semitic (Akkadian) name of the later Utnapishtim of Middle Babylonian and Neo-Babylonian.
But even older legend of Utnapishtim and Atrahasis, from Sumerian, where his name is Ziusudra, the original Flood hero.
Ziusudra is only alluded to in one Sumerian poem, the Death of Gilgames (or Bilgames, as it transliterated from Sumerian), dated to the late 3rd millennium BCE. There are 5 distinct Sumerian poems of Gilgames, four of which later reappeared in the Babylonian Epic of Gilgamesh, so we know of the origin of Epic.
Although there are not much detail about Gilgames' journey to see Ziusudra, like the epic's tablets 9 to 11 of the Standard Version, where it narrated Gilgamesh's journey and encounter with Utnapishtim, we do know that it is obvious the Sumerians were aware of such tale.
Ziusudra and the Flood also appeared more fully in the Sumerian text, known today as the Eridu Genesis, however these tablets are badly fragmented. But what is clear, even with the damaged tablets, is that there are too many similarities to the later Akkadian or Old Babylonian Epic of Atrahasis, and to the Neo-Assyrian Standard Version.
Ziusudra also appeared in one of the Sumerian King List, as well as tablet known as the Instructions of Shuruppak.
Shuruppak is the name of a city-state, as well as the name of a king who ruled that city, supposedly Ziusudra's father.
A lot of translations to Sumerian literature are available free at
The Electronic Text Corpus of Sumerian Literature (
ETCSL), at this
link:
I have my own translations in a single book,
Harps That Once...: Sumerian Poetry in Translation, by Thorkild Jacobsen (Yale University Press, 1997).
For a collection of both Standard Version of the Epic of Gilgamesh, that also of other tablets, including the Sumerian poems of Bilgames, I would recommend
The Epic of Gilgamesh: A New Translation, by Andrew George (Penguin Classics, 1999).
For the Epic of Atrahasis and other Babylonian texts, there is a book by Stephanie Dalley -
Myths From Mesopotamia (Oxford World's Classics, 2000). I think it is now available on-line.
I hoped that these information help.