Passage 9.1.1
Ἀθηναίοις δὲ ἡ Βοιωτία καὶ κατὰ ἄλλα τῆς Ἀττικῆς ἐστιν ὅμορος, πρὸς δὲ Ἐλευθερῶν οἱ Πλαταιεῖς. Βοιωτοὶ δὲ τὸ μὲν πᾶν ἔθνος ἀπὸ Βοιωτοῦ τὸ ὄνομα ἔσχηκεν, ὃν Ἰτώνου παῖδα καὶ νύμφης δὴ Μελανίππης, Ἴτωνον δὲ Ἀμφικτύονος εἶναι λέγουσι· καλοῦνται δὲ κατὰ πόλεις ἀπό τε ἀνδρῶν καὶ τὰ πλείω γυναικῶν. οἱ δὲ Πλαταιεῖς τὸ ἐξ ἀρχῆς ἐμοὶ δοκεῖν εἰσιν αὐτόχθονες· ὄνομα δέ σφισιν ἀπὸ Πλαταίας, ἣν θυγατέρα εἶναι Ἀσωποῦ τοῦ ποταμοῦ νομίζουσιν.
Boeotia borders the Athenians in various places along Attica, and near Eleutherae, the Plataeans are neighbors. As for the Boeotians, the whole nation received its name from Boeotus, who was the son of Itonus and the nymph Melanippe; Itonus, they say, was the son of Amphictyon. The people of the individual cities are named chiefly after men, but in most cases after women. The Plataeans, however, seem to me from the beginning to have been indigenous; their name comes from Plataea, whom they regard as a daughter of the river Asopus.