in gilgamesh, there are many references to events that also took place in The Bible as well as other stories and legends. so you'd have to specify your question by actually asking about a specific event in the epic as they are all spread out throughout the middle-eastern region
The Epic of Gilgamesh is the best-known surviving example of Mesopotamian literature.
The Epic of Gilgamesh comes from Mesopotamia, most likely the Sumerian period around 3000BC.
Epic of Gilgamesh: Mesopotamia The Book of the Dead: Egypt
Certainly the story of Noah's Flood is remarkably similar to the Flood story of Umapishtim in the much older Sumerian Epic of Gilgamesh. On that evidence, the Epic of Gilgamesh is the most likely source for the story of Noah's Flood.
C. 6,000 bc