I know Homer isn't the best source for historical accuracy, but his works aren't complete fantasies. He does have great knowledge and awareness of Greece's geographic surroundings, which leads me to assume that he wouldn't make up some random country or city-state if it wasn't crucial to his plot. I know Phaecia was a made up utopian society in the Odyssey, but it was needed to carry the plot.
Ethiopia was mentioned several times in the Iliad and the Odyssey with no great detail. It seems unlikely to me that the ancient Greeks had contact with Ethiopia, or Axum if I'm guessing the right timeline, unless there was a different civilization named Ethiopia at the time??
Homer mentions Αἰθίοψ (ie, Ethiopians) a number of times in the Iliad and the Odyssey who live in a land of wealth and plenty and are favored and frequently visited by the gods. The term "Ethiopian" comes to us from Greek (that is, it is their word for these people, not what they called themselves), from the verb αἴθω: to burn and ὄψ: face. But it doesn't refer to the place or people we would now call Ethiopia/ns. It refers to the Nubian empire of Kush, with its capital at Napata which controlled Egypt for about a hundred years from the mid-8th century.
The Greeks of the "dark ages" actually had a very wide range of contact, northern africa, the near east, up into the Black Sea and there was a lot of trade and exchange, so while the Greeks didn't exactly have an entirely accurate picture of other cultures, the contact is greater than people assume.
If you're interested in the Greek perception of these Ethiopians and exactly who they were and the full extent of their kingdom, Frank Snowden wrote a lot about these issues in the 70s and 80s, his books Blacks in Antiquity and Before Color Prejudice might be of interest.