Passage 7.18.1
σταδίους δὲ ὅσον τεσσαράκοντα προελθόντι ἐκ Δύμης ποταμὸς Πεῖρος ἐς θάλατταν κάτεισι, καὶ Ἀχαιῶν πόλις ποτὲ Ὤλενος ᾠκεῖτο παρὰ τῷ Πείρῳ. ὁπόσοι δὲ ἐς Ἡρακλέα καὶ τὰ ἔργα αὐτοῦ πεποιήκασιν, ἔστιν οὐκ ἐλάχιστά σφισι δείγματα τοῦ λόγου Δεξαμενὸς ὁ ἐν Ὠλένῳ βασιλεὺς καὶ ὁποίων Ἡρακλῆς παρʼ αὐτῷ ξενίων ἔτυχε. καὶ ὅτι μὲν ἦν πόλισμα ἐξ ἀρχῆς μικρὸν ἡ Ὤλενος, μαρτυρεῖ τῷ λόγῳ μου καὶ ἐλεγεῖον ἐς Εὐρυτίωνα Κένταυρον ὑπὸ Ἑρμησιάνακτος πεποιημένον· ἀνὰ χρόνον δὲ τοὺς οἰκήτορας ἐκλιπεῖν ὑπὸ ἀσθενείας φασὶ τὴν Ὤλενον καὶ ἐς Πειράς τε καὶ ἐς Εὐρυτειὰς ἀποχωρῆσαι.
About forty stadia from Dyme, the river Peirus meets the sea, and beside the Peirus once stood Olenos, a city of the Achaeans. Among those who have recounted the deeds of Heracles and his labors, Dexamenos, king in Olenos, offers no small confirmation of their stories and of the hospitality that Heracles received from him. That Olenos was originally a small settlement is confirmed by what Hermesianax wrote in his elegy about Eurytion the Centaur. In due course, the inhabitants are said to have abandoned Olenos due to its weakness and migrated to Peirai and Euryteiai.