On of the oldest literate documents in Greek are the Iliad and Odyssey. They are written around 800 BC and they are the result of a form of oral poetry that went on for many many years from mouth to mouth. It became something like the holy script of the Greeks and a lot of the mythological stories about the gods, the city borders and the well known hero’s were out of these scripts.
The “Iliad” is about the last years of the Trojan war, while the “Odyssey” is about the return of Odysseus from Trojan to Ithaca and the adventures which happened to him during this time.
It is said that they are composed by the most famous ancient Greek poet Homer, who taught on the island of Chios. But there are many doubts, not just because of the many stylistic differences of both works. With the time many things were added, many things adapted to the actual time, and inappropriate things were just taken out.
That´s why you can assume that the two documents have more than one composer.