; based on craftsmanship, experts estimate his age as between 6 and 7 at the time. On July 26, 1951, during excavations in
Novgorod, Nina Fyodorovna Akulova discovered the first Russian birch bark manuscript in a
stratigraphic layer dated to around the year 1400. As of 2018, a total of 1,222 items have been discovered in 12 cities, of which 1,113 were found in Novgorod. In Russia, outside of Novgorod, the others were found in
Staraya Russa (49),
Torzhok (19),
Smolensk (16),
Pskov (8),
Tver (5),
Moscow (4),
Ryazan (1), and
Vologda (1). Outside of Russia, the rest were found in
Mstsislaw (2) and
Vitebsk (1) in Belarus, and in
Zvenyhorod (3) in Ukraine. Of the birch bark documents unearthed in Russia, 90% were found in Novgorod and 97% were found in the same historic region as Novgorod. ; photograph In Russian, the study of birch bark letters is informally known as
berestologiya, from the word
beryosta for the outer birch bark. Less than 3% of medieval Novgorod has been systematically excavated, and
Valentin Yanin, the head of the Novgorod Archaeological Expedition, estimated that more than 20,000 remain to be discovered in Novgorod alone. Although the birch bark letters do not contain explicit dates, archaeologists have been able to date them with an accuracy of 10 to 15 years using methods including
stratigraphy and
dendrochronology. They can be dated even more precisely if historical names or events are mentioned. The late discovery of birch documents, as well as their amazing state of preservation, is explained by a deep culture layer in Novgorod (up to eight meters, or 25 feet) and heavy waterlogged
clay soil which prevents the access of
oxygen. Serious excavations in Novgorod started only in 1932, although some attempts had been made in the 19th century. The earliest possible mention of their existence comes from authorities cited by
Ibn al-Nadim, who described "Russians" writing upon "white wood" and gave an example of a "Russian" system of writing, adding, "I do not know whether these are words or single letters". Over two hundred
styluses have also been found, mostly made of
iron, some of
bone or
bronze.
Andrey Zaliznyak distinguished the manuscripts in Novgorod from "supra-dialectal Old Russian". Other manuscripts in Novgorod have also shown distinct
north Russian dialect forms. As
Church Slavonic was used in liturgical and religious writing, while a supra-regional variety was used for trade, it is unclear to what extent Novgorodians at the time would have considered them to have been separate languages or distinct registers of a single language. In addition, there is some variation in birch bark letters due to a lack of standardization that is seen with modern literary languages. Some texts are also written with a mixture of Church Slavonic and
Old Novgorodian, but others are written in a pure vernacular. The language found in the birch bark manuscripts represents the closest approximation to the vernacular Old Russian language. Since the manuscripts were written by laypeople and consist of casual notes, it has been suggested that there was widespread literacy across large segments of urban society in medieval Russia; according to one estimate, 20% of the urban male population in Russian city-states were literate around the mid-13th century. The contents of the birch bark writings included not only religious writings but also document death of princes, conclusions of peace, dignitary arrivals, folk verses and local proverbs, even casual doodles. While legal related matters include accusations, witnesses and the procedure of evidence, payments and fines, theft, fraud as well as wife-beating. One mundane personal writing reads "Sell the house and come to Smolensk or Kiev; bread is cheap; if you cannot come, write to me about your health". One of the smallest birch bark letters found is no. 79, which is no larger than 6 x 1.5cm, while no. 397 is 4.6 x 2.6cm. On the opposite side of the scale, no. 519 is 47.2 x 16cm. Of those where the texts have been preserved in their entirety, most are no more than 20 words long, with a few exceeding 50 words. The longest one, found in Moscow (Moscow 3), contains 52 lines and about 370 words. The second longest, no. 531, is 166 words. The majority of surviving birch bark letters have missing text, with only a quarter of the entire corpus having complete texts. ==Finnic manuscripts==