Once again to the problem of the chronology of the emergence and decay of Slavic nasal vowels

We show that already in the very first examples of Slavic vocabulary that has come down to us in the 6th–8th centuries. (Slavic onomastics in Byzantine sources, Slavic toponymy in Greece, Slavisms in the Romanian language) there is a fairly large layer of terms with nasal vowels. This quite convincingly suggests that the phonetic phenomenon under discussion arose in Proto-Slavic times, even before the Slavs themselves appeared on the historical arena. Analyzing the decay of nasal vowels in the East Slavic language, we show that the generally accepted argument about the disappearance of these vowels in the 10th century, based on the names of the Dnieper rapids by Constantine Porphyrogenitus (Νεασήτ and Βερούτζη), is very weak. Data from Byzantine sources, for example, the mention of the name Svyatoslav in the form Σφενδοσθλάβος/Σφενδοσθλάβον in the treatise of Leo the Deacon, describing the events of 971/972, convincingly indicate that nasality in princely anthroponymy in the 10th century. was still preserved. We show that the thesis about the disappearance of nasal vowels in Rus' in the 10th century, which has acquired the character of an imperative ideologeme in the modern linguistic environment, is incorrect both in form and in essence. The chronology of nasal vowel decay was determined by the specific vowel. Anthroponyms with small yus retained their nasality until the second — third decades of the 11th century. Using the example of the lexeme сѫбота, we demonstrate that its nasal phonetics were borrowed into the Kipchak dialects during the first contacts of the Russian princes with the Cumans in the middle of the 11th century. The term shambe / şənbə / šenbe will become the basis for designating the days of the week in Iranian and a number of Turkic languages. Nasality in the pronunciation of words with a major yus in the Old Russian language was lost only in the last decades of the 11th century.