The 9th-century Bulgarian writer Chernorizets Hrabar, in his work An Account of Letters, briefly mentions that, before Christianization, Slavs used a system he had dubbed "strokes and incisions" or "tallies and sketches" in some translations. He also provided information critical to Slavonic palaeography with his book. Another contemporaneous source, Thietmar of Merseburg, describing a temple on the island of Rügen, a Slavic pagan stronghold, remarked that the idols there had their names carved out on them. Ahmad ibn Fadlan describes the manners and customs of the Rus, who arrived on a business trip in Volga Bulgaria. After a ritual ship burial of their dead tribesmen, Rus left an inscription on the tomb: However, Ibn Fadlan doesn't leave many clues about the ethnic origin of the people he described.
Evidence from archaeology
In 1949, a Kerch amphora was found from Gnezdovo in Smolensk Oblast with the earliest inscription attested in Old East Slavic. The excavator has inferred that the word гороухща, inscribed on the pot in Cyrillic letters, designates mustard that was kept there. This explanation has not been universally accepted and the inscription seems to be open to different interpretations. The dating of the inscription to the mid-10th century suggests a hitherto unsuspected popularity of the Cyrillic script in pre-Christian Rus.
The modern Slavic word for "to write", :wikt:Reconstruction:Proto-Slavic/pьsati derives from a Common Balto-Slavic word for "to paint, smear", found in Lithuanian:wikt:piešti "paint, write", paĩšas "smudge", puišinas "sooty, dirty", from the same root as Old Slavic:wikt:Reconstruction:Proto-Slavic/pьstrъ "coloured", ultimately from a PIE root' "speckled, coloured". "smearing, painting", whereas the ancient Slavic word for writing, incising / action of writing, engraving was "ryt", "ryć" meaning "engrave" just like the English word "write" descending from rītan that was transferred through the Old English*rītan into the English vocabulary'. The other Germanic languages use terms derived from Latin. A Slavic term for "to incise" survives in OCS:wikt:жрѣбъ and "skrobać" Scipta Slaviae originally the incision on a wooden chip used for divination.
Evidence against
In the Vita Cyrilli, Rastislav, the duke of Moravia, sent an embassy to Constantinople asking Emperor Michael III to send learned men to the Slavs of Great Moravia, who being already baptised, wished to have the liturgy in their own language, and not Latin and Greek. Emperor called for Constantine and asked him if he would do this task, even though being in poor health. Constantine replied that he would gladly travel to Great Moravia and teach them, as long as the Slavs had their own alphabet to write their own language in, to which the Emperor replied that not even his grandfather and father and let alone he could find any evidence of such an alphabet. Constantine was distraught, and was worried that if he invents an alphabet for them he'll be labelled a heretic. Even if some form of writing existed among the Slavs in previous centuries, by the 9th century the learned men in the Eastern Roman Empire were not aware of its existence in any of the Slavic lands that they had sent missionaries or ambassadors to. Either this writing had died out or it was not a real form of writing, but rather just "tallies and sketches" as mentioned in Chernorizets Hrabar's An Account of Letters, using which books could not be written.
