Prometheus Bound (Greek Tragedy in New Translations) by Aeschylus, Oxford University Press; Reprint edition (December 1, 1989), p. 68-69
"You'll come, then, to a land at the world's end where tribes of black people live, where the Fountains of the Sun gush and the River Aithiops flows. Follow that river's bank, till you come upon sheer waterfall plunging down from the Byline Hills, hills bubbling the sweet blessed waters of the Nile."
Aithiops: Greek translation for Ethiopia.
Prometheus was a titan, the race of old gods who reigned before Zeus and the Olympians.
Bust of Aeschylus from the Capitoline Museums, Rome