When Israel was conquered by Nebuchadnezzer in the 6th century BC, he deported the Jews to Babylon. They were assimlated into that culture and were generally well educated people. When the Persians conquered Babylon the Jews were allowed to return to Israel.
When they came back, they then had the Torah, much of which was influenced by the Babylonian culture. So Genesis places Eden near Babylon, and Noah is a variation on the Babylonian story of Gilgamesh.
Thanks for the info. I knew about the story of Gilgamesh and that it probably referred to the same event as Genesis, but never was clear on how the Jews got from Eden to Israel.