Passage 1.39.4
Ἐλευσῖνι δὲ ἤδη πλησιόχωρος ἡ καλουμένη Μεγαρίς· τῆς Ἀθηναίων ἦν καὶ αὕτη τὸ ἀρχαῖον, Πύλα τοῦ βασιλέως καταλιπόντος Πανδίονι. μαρτύρια δέ μοι τάφος τε Πανδίονος ἐν τῇ γῇ καὶ Νῖσος Αἰγεῖ μὲν πρεσβυτάτῳ τοῦ παντὸς γένους παραχωρήσας Ἀθηναίων ἄρχειν, αὐτὸς δὲ Μεγάρων καὶ τῆς ἄχρι Κορίνθου βασιλεύειν ἀξιωθείς· Νίσαιά τε ἔτι καὶ νῦν Μεγαρεῦσιν ἐπίνειον ἀπʼ αὐτοῦ καλεῖται. Κόδρου δὲ ὕστερον βασιλεύοντος στρατεύουσιν ἐπʼ Ἀθήνας Πελοποννήσιοι· καὶ ὡς οὐδὲν ἀποδειξάμενοι λαμπρὸν ἐκομίζοντο ὀπίσω, Μέγαρα Ἀθηναίων ἑλόντες Κορινθίων καὶ τῶν ἄλλων συμμάχων τοῖς ἐθέλουσιν ἔδωκαν οἰκῆσαι.
Bordering close upon Eleusis is the region called Megaris. In earlier times this also belonged to the Athenians, for King Pylas relinquished it to Pandion. As evidence I point both to Pandion's tomb in that land and to Nisus himself, who yielded rule over Athens to Aegeus, the eldest of the whole family, but retained for himself Megara and the territory as far as Corinth, ruling as king. Indeed, even now the port Nisaea, which serves the Megarians, bears his name. Later, in the reign of Codrus, the Peloponnesians attacked Athens; and when they returned home without having achieved any notable success, they captured Megara from the Athenians and gave it to the Corinthians and other allies who wished to settle there.