How Latin-derived month names became established in Russia

However, for a long time, they coexisted with the old calendar and Slavic names, which described the weather, the natural world or agricultural activities.

Examples include ‘prosinets’ (January – the sky appeared blue), ‘sechen’ (February – the time for cutting down trees), ‘berezozol’ (April – the collection of birch sap), ‘serpen’ (August – harvest time) and ‘listopad’ (October – when trees shed their leaves for winter) and others. There was no single, standardized set of these names; variations appeared across different regions and sources (often depending on the local climate), but, on the whole, people generally understood one another quite well.

From the 10th century until the end of the 15th century, the New Year in Old Russia was officially counted starting in March. This tradition was directly linked to the agricultural cycle: March marked the awakening of nature and the beginning of spring farm work.

The March-based calendar system was officially abolished in 1492, when the Moscow Ecumenical Council decided to shift the start of the year to September 1, following the Byzantine ecclesiastical tradition.

The transition of the New Year from September 1 to January 1 took place during Peter the Great’s calendar reform. Until the end of the 17th century, Russia officially used a chronology based on the "creation of the world". Peter I, who sought to modernize the country and bring it closer to Europe, issued a decree in December 1699: after December 31, 7208, "from the creation of the world," January 1, 1700, was to be counted "from the birth of Christ".

From that time on, official documents began to record dates based on the birth of Christ, using the Latin names for the months – names that had already become familiar by then. Nevertheless, in many Slavic languages, the traditional Slavic names for the months remain in use to this day.