Dnieper-Oka language
The Dnieper-Oka language is one or several extinct Baltic languages, the existence of which is indicated by toponymic data. It occupied the upper reaches of the Daugava, the basins of the upper Dnieper and Desna, the upper and middle Oka and the Seym. Beginning in the 7th and 8th centuries, the Baltic dialects of the region were replaced by Old East Slavic. The only known subdivision of the Dnieper-Oka language is the Golyad language.
Language area
Hydronymics indicate the ancient presence of the Balts in two regions that were occupied by the East Slavs at the beginning of historical time:Dnieper - The most extensive, moreover, it is divided into separate relatively independent hydronymic areas, covering the northern half of the Dnieper basin from its sources to Kyiv and numbering up to five to six hundred reliable hydronymic balticisms. Although their distribution throughout the Dnieper basin is uneven and strong condensations alternate with spaces that are significantly sparse in relation to balticisms, in general there is reason to speak of the continuity of the Baltic hydronymic element in the Dnieper basin.Oksky - The Oka basin, several hundred Baltic hydronyms + abundant borrowings in the Finno-Volgaic languages. However, along the Oka, the sparseness of Balticisms in the upper reaches, especially their practical absence within the Ryazan and Nizhny Novgorod oblasts, is combined with the density of the Baltic hydronymic layer within the Kaluga and Moscow oblasts and, surprisingly, with the thickening of Balticisms in the very lower reaches of the Oka. At the end of the 20th century, studies by Yuri Otkupshchikov and Vladimir Toporov revealed the widespread distribution of Baltic hydronyms in the Moscow, Tver and Smolensk oblasts, less often in the Kaluga, Tula and Oryol oblasts.Middle Volga region
The discovery of obvious hydronymic Baltisms in the Middle Volga region has brought to the fore the problem of the eastern boundary of the Balts' settlement. Vladimir Napolskikh considers the Imenkovo culture of the Middle Volga region to be the eastern flank of the Balto-Slavic cultural and linguistic community, although this view is highly controversial.According to Péter Hajdu, the early contacts of the Volga Finns with the Balts, on the one hand, and the ancestors of the Indo-Iranians, on the other, spatially belong to the Middle Volga region, and in time - to the common Finnish era between the beginning of the 1st millennium BC and the 6th-8th centuries AD. These contacts are evidenced by the abundant Balticisms in Finnic, and partly in the Finno-Volgaic languages, and, moreover, individual borrowings in the Baltic languages, which could have been adopted from the Finno-Volgaic languages, such as, for example, Lithuanian sóra and Latvian sāre "millet", the source of which was the original *psārā ; compare Erzya śora, Moksha suro "bread, grain".