"Arrian wrote me thus"

This is the Periplus Ponti Euxini (Circumnavigation of the Black Sea), completed by Arrian (Lucius Flavius Arrianus Xenophon) between 130-131 AD. It is a description of a voyage made by Arrian, and was intended both as an exercise in military intelligence (it would have been placed in the hands of the commander of any expeditionary force sent to the region), but copies of it could also have served as a guide for navigators. The description of the southern coast is far more detailed than that of the northern. The original Greek text can be seen at http://remacle.org/bloodwolf/historiens/arrien/periplegr.htm and an English translation at http://en.wikisource.org/wiki/The_Periplus_of_the_Euxine_Sea.