Passage 3.2.2
ἐπὶ δὲ Ἐχεστράτου τοῦ Ἄγιδος βασιλεύοντες ἐν Σπάρτῃ Κυνουρέας τοὺς ἐν τῇ ἡλικίᾳ Λακεδαιμόνιοι ποιοῦσιν ἀναστάτους, αἰτίαν ἐπενεγκόντες ὡς τὴν Ἀργολίδα συγγενῶν σφισιν ὄντων Ἀργείων λῃσταί τε ἐκ τῆς Κυνουριακῆς κακουργοῖεν καὶ αὐτοὶ καταδρομὰς ἐκ τοῦ φανεροῦ ποιοῖντο ἐς τὴν γῆν. λέγονται δὲ οἱ Κυνουρεῖς Ἀργεῖοι τὸ ἀνέκαθεν εἶναι, καὶ οἰκιστήν φασιν αὐτῶν Κύνουρον γενέσθαι τὸν Περσέως.
During the reign of Echestratus son of Agis in Sparta, the Lacedaemonians forcibly expelled the Cynurians who were of military age, alleging as justification that while the Argives, their own kinsmen, inhabited Argolis, raiders from Cynuria continually committed criminal acts, and the Cynurians themselves openly launched incursions into Argive territory. It is said, moreover, that the Cynurians were originally Argives, and they claim that their founder was Cynurus, son of Perseus.