Stone of Tmutarakan

The Stone of Tmutarakan is a marble slab engraved with the words "In the year 6576 [ A.M., 1068 A.D] the sixth of the Indiction, Prince Gleb measured across the sea on the ice from Tmutarakan to Kerch 14,000 sazhen" (Old East Slavic: " 6576 6 [] 10000 4000 []", Russian translation: " 6576 6 14000 "). A sazhen, an old Rus unit of length, was equal to seven feet (or corresponded roughly to a fathom); thus the Kerch Straits, according to the stone, were 88,000 feet or 18.5 miles across (that is, from Kerch to Tmutarakan — the straits themselves are only 4.5 miles wide at their narrowest point, but the distance from the site of Tmutarakan to modern-day Kerch is about 15 miles) The tenth-century Byzantine Emperor Constantine Porphyrogenitus wrote that the straits were the equivalent of 18 miles across, and this might explain why that measurement appears on the stone, although it is unclear if an eleventh-century prince in Rus would have had access to that information; this uncertainty calls the stone's authenticity into question. The Prince Gleb referred to in the inscription was Gleb Svyatoslavich, then prince of Tmutarakan. Gleb was later Prince of Novgorod the Great, where he saved Bishop Fed

Monument data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).