Sicyonians were Dorians
That the Sicyonians, those of the neighboring district, were Dorians is evident in many places besides Diodorus Siculus at 7.9.1 (“Fragments of Book VII” in the Loeb Library edition) where he states: “it remains for us to speak of Corinth and of Sicyon, and of the manner in which the territories of these cities were settled by the Dorians.”
Strabo speaks of the rebuilding of Corinth as such was ordered by Caesar, which began about 44 B.C., and states that “it was restored again, because of its favorable position, by the deified Caesar, who colonised it with people that belonged for the most part to the freedmen class” (8.6.23). Yet Diodorus Siculus (in “Fragments of Book XXXII” in the Loeb Library edition) is recorded as telling us further:
“Gaius Iulius Caesar (who for his great deeds was entitled divus), when he inspected the site of Corinth, was so moved by compassion and the thirst for fame that he set about restoring it with great energy. It is therefore just that this man and his high standard of conduct should receive our full approval and that we should by our history accord him enduring praise for his generosity. For whereas his forefathers had harshly used the city, he by his clemency made amends for their unrelenting severity, preferring to forgive rather than to punish” (32.27.3).