Passage 8.6.1
τὰ μὲν δὴ ἐς τοὺς βασιλεῖς πολυπραγμονήσαντί μοι κατὰ ταῦτα ἐγενεαλόγησαν οἱ Ἀρκάδες· κοινῇ δὲ Ἀρκάσιν ὑπῆρχεν ἐς μνήμην τὰ μὲν ἀρχαιότατα ὁ πρὸς Ἰλίῳ πόλεμος, δεύτερα δὲ ὁπόσα ἀμύνοντες Μεσσηνίοις Λακεδαιμονίων ἐναντία ἐμαχέσαντο· μέτεστι δὲ καὶ πρὸς Μήδους σφίσιν ἔργου τοῦ ἐν Πλαταιαῖς.
Regarding the kings, the Arcadians, when I investigated the matter, provided me with the genealogies I have described above. As for common memories among the Arcadians, the most ancient event was the Trojan War; next were the battles they fought against the Spartans while assisting the Messenians; and they also shared in the action against the Medes at Plataea.