Middle Russian language

Middle Russian is the historical stage of the Russian language that was spoken and written from the 14th to the 17th centuries. It developed following the dialectal fragmentation of Old East Slavic into the distinct Russian and Ruthenian branches, and lasted until the orthographic and literary reforms introduced by Peter the Great. In Russian scholarly literature, this period is natively referred to as Old Russian (старорусский язык) or Old Great Russian (старовеликорусский язык). In English, "Old Russian" is typically reserved for the preceding Old East Slavic stage (7th–14th centuries) to maintain the chronological distinction between Old, Middle, and Modern Russian. These various terms are primarily used by linguists to classify units of language and determine their historical age or the period of their first written record. The Middle Russian era is conventionally divided into two distinct subperiods: Early Middle Russian (14th–15th centuries) and Late Middle Russian (16th–17th centuries).