Passage 10.31.7
παρὰ δὲ τῷ Μέμνονι καὶ παῖς Αἰθίοψ πεποίηται γυμνός, ὅτι ὁ Μέμνων βασιλεὺς ἦν τοῦ Αἰθιόπων γένους. ἀφίκετο μέντοι ἐς Ἴλιον οὐκ ἀπʼ Αἰθιοπίας ἀλλὰ ἐκ Σούσων τῶν Περσικῶν καὶ ἀπὸ τοῦ Χοάσπου ποταμοῦ, τὰ ἔθνη πάντα ὅσα ᾤκει μεταξὺ ὑποχείρια πεποιημένος· Φρύγες δὲ καὶ τὴν ὁδὸν ἔτι ἀποφαίνουσι διʼ ἧς τὴν στρατιὰν ἤγαγε τὰ ἐπίτομα ἐκλεγόμενος τῆς χώρας· τέτμηται δὲ διὰ τῶν μονῶν ἡ ὁδός.
Next to Memnon, too, a figure of a naked Ethiopian boy has been sculpted, since Memnon was king of the Ethiopian race. He came to Troy, however, not from Ethiopia but from Susa in Persia and from the river Choaspes, having subdued all the peoples inhabiting the lands in between. Indeed, the Phrygians even still point out the road along which he led his army, selecting the shortest routes through the countryside; the road itself is cut through the isolated regions.