Statistics for occurrence #1 of “Caucasus” in book 3, chapter 97, section 4 of Herodotus, The Histories:
...p://www.w3.org/TR/xhtml1/strict"> Gifts were also required of the Colchians and their neighbors as far as the Caucasus mountains (which is as far as the Persian rule reaches, the country north of the Caucasus paying no regard to the Persians); these were rendered every four years and are still rendered, namely, a hundred boys and as many maids.
...