Abstract
This work is intended to present to the academic community in Brazil the main aspects of the language called Old East Slavic, widely spoken by the East Slavic populations from the 5th century CE to the 16th century CE. From Old East Slavic come all three modern East Slavic languages: Russian, Ukrainian and Belarusian. By explaining the outlines of Old East Slavic, the author hopes to help readers understand the factors that lead to the formation of 18th and 19th-century Russian literary language. The article also tries to explain what makes Old East Slavic different and independent from Old Church Slavonic, its closest relative. Therefore, this work is a simplified description of Old East Slavic as it was spoken before the Mongol Invasion.
