More likely it was handed down via oral tradition.
It's a bit farfetched to require a written document to be memorized, turned into an oral tradition, and then written down centuries later in a different language by Moses. It's much easier to have the written documents (clay tablets) carried from Sumer to Egypt where they could be "read" (translated) by Moses (and his associates) several hundred years later.
In fact, the Hebrew tradition post-Moses is that they carried about the tablets Moses received from God in the Ark of the Covenant.