Histories 4.38. C.f. James Rennell, The geographical system of Herodotus examined and explained, Volume 1, Rivington 1830, p. 244.
according to Strabo (Geographica 11.7.4) even at the time of Alexander, “it was agreed by all that the Tanais river separated Asia from Europe” (ὡμολόγητο ἐκ πάντων ὅτι διείργει τὴν Ἀσίαν ἀπὸ τῆς Εὐρώπης ὁ Τάναϊς ποταμός; c.f. Duane W. Roller, Eratosthenes' Geography, Princeton University Press, 2010, ISBN 978-0-691-14267-8, p. 57)
Geographia 7.5.6 (ed. Nobbe 1845, vol. 2, p. 178)) Καὶ τῇ Εὐρώπῃ δὲ συνάπτει διὰ τοῦ μεταξὺ αὐχένος τῆς τε Μαιώτιδος λίμνης καὶ τοῦ Σαρματικοῦ Ὠκεανοῦ ἐπὶ τῆς διαβάσεως τοῦ Τανάϊδος ποταμοῦ.
“And [Asia] is connected to Europe by the land-strait between Lake Maiotis and the Sarmatian Ocean where the river Tanais crosses through”.
Douglas W. Freshfield, "Journey in the Caucasus", Proceedings of the Royal Geographical Society, Volumes 13-14, 1869.
Cited as de facto convention by Baron von Haxthausen, “Transcaucasia” (1854); review Dublin university magazine
