Plato, Laws 708c

τῇ μὲν ῥᾴω κατοικίζεσθαί τε καὶ νομοθετεῖσθαι, τῇ δὲ χαλεπώτερα. τὸ μὲν γὰρ ἕν τι εἶναι γένος ὁμόφωνον καὶ ὁμόνομον ἔχει τινὰ φιλίαν, κοινωνὸν ἱερῶν ὂν καὶ τῶν τοιούτων πάντων, νόμους δʼ ἑτέρους καὶ πολιτείας ἄλλας τῶν οἴκοθεν οὐκ εὐπετῶς ἀνέχεται, τὸ δʼ ἐνίοτε πονηρίᾳ νόμων ἐστασιακὸς καὶ διὰ συνήθειαν ζητοῦν ἔτι χρῆσθαι τοῖς αὐτοῖς ἤθεσιν διʼ ἃ καὶ πρότερον ἐφθάρη, χαλεπὸν τῷ κατοικίζοντι

All such cases are in one way easier to manage, as regards settling and legislation, but in another way harder. In the case where the race is one, with the same language and laws, this unity makes for friendliness, since it shares also in sacred rites and all matters of religion; but such a body does not easily tolerate laws or polities which differ from those of its homeland. Again, where such a body has seceded owing to civil strife due to the badness of the laws, but still strives to retain, owing to long habit, the very customs which caused its former ruin, then, because of this, it proves a difficult and intractable subject for the person who has control of its settlement and its laws.