Ancient authors: Ephoros of Kyme (FGrHist / BNJ 70 F113) as cited by Strabo, Geography 5.2.4 (link to Greek text and full English translation)
Comments: Ephoros (or: Ephorus) of Kyme’s works (ca. 340 BCE) survive only in brief citations by others, and in this case Strabo (before 18 CE) cites Ephoros’ views on the origins of the Pelasgians and their relation to Arkadians and other Greeks, as well as their colonization of various areas in Greece.
Source of the translation: H.L. Jones, Strabo, vol. 2 (LCL; Cambridge, MA: HUP, 1923), public domain, adapted by Harland.
Regarding the Pelasgians, almost everyone agrees that, first of all, some ancient tribe (phylē) of that name spread throughout all of Greece, and particularly among the Aiolians of Thessaly. Again, Ephoros says that he is of the opinion that, since they were originally Arkadians, they chose a military life. He is of the opinion that, because they converted many peoples to the same mode of life, they imparted their name to everyone and for this reason acquired a great reputation not only among Greeks but also among all other peoples to whom the Pelasgians happen to come.
For example, the Pelasgians prove to have been colonizers of Krete, as Homer says. Anyways, Odysseus says to Penelope: “But one tongue with others is mixed; there dwell Achaians, there Kretans of the old descent, proud of heart, there Kydonians and Dorians as well, of waving plumes, and goodly Pelasgians” [Homer, Odyssey 19.175-177]. Thessaly is called “the Pelasgian Argos” (by which I mean that part that lies between the outlets of the Peneios river and Thermopylai as far as the mountainous country of Pindos) on account of the fact that the Pelasgians extended their rule over these regions. Further, the Dodonaean Zeus is by the poet himself named “Pelasgian”: “O Lord Zeus, Dodonaian, Pelasgian” [Homer, Iliad 16.233]. Furthermore, many have called the Epeirian peoples (ethnē) “Pelasgian,” because in their opinion the Pelasgians extended their rule even as far as that. Further still, because many of the heroes were called “Pelasgians” by name, the people of later times have, from those heroes, applied the name to many of peoples. For example, they have called the island of Lesbos “Pelasgia,” and Homer has called “Pelasgians” the neighbours of those Kilikians who lived in the Troad: “And Hippothous led the tribes (phylē) of spear-fighting Pelasgians, those Pelasgians who inhabited deep-soiled Larissa.” [Homer, Iliad 2.840-841].
But Ephoros’ authority for the statement that this tribe (phylē) originated in Arkadia was Hesiod. For Hesiod says: “Sons were born of god-like Lykaon, who, at one point, was begotten by Pelasgos.” Again, Aischylos, in his Suppliants (249-253), or else his Danaan Women, says that the descent group (genos) of the Pelasgians originated in that Argos which is around Mykenai. According to Ephoros, the Peloponnesos was also called “Pelasgia.” Furthermore, in his Archelaos Euripides says: “Danaos, the father of fifty daughters, on coming into Argos, took up his abode in the city of Inachos. Throughout Greece, he laid down a law that all people previously named Pelasgians were to be called Danaians.” And again, Antikleides says that they were the first to settle the regions around Lemnos and Imbros, and indeed that some of these sailed away to Italy with Tyrrhenos the son of Atys. The compilers of the histories of The Land of Atthis give accounts of the Pelasgians, believing that the Pelasgians were in fact at Athens too, although the Pelasgians were by the Attic people called “Pelargians,” the compilers add, because they were wanderers and, like birds, resorted to those places wherever chance led them.