I think the first real "book" of literature is the
Epic of Gilgamesh. It's still available in a modern translation. A very moving story about the loss of a dear friend, grief, and coming to terms with the reality of death.
It comes from the fertile crescent, the area between the rivers Nile and Euphrates, where civilization originated.
My copy, a translation by Stephen Mitchell, says in the introduction that it "is the oldest story in the world, a thousand years older than the Bible or the Iliad (by Homer). Its hero was a historical king who reigned in the Mesopotamian city of Uruk in about 2750 B.C.E." That's pretty darn old!