1. Ruthenian language, also known (less precisely) as Russian, is a Slavic language spoken in Ruthenia or Russia (Rus) in Middle Ages. From Ruthenian evolved Russian, Ukrainian, Belarusian. Sometimes Carpatho-Ruthenian (Rusyn) is added into this list, however most Slavic linguists do not recognize Ruthenian as a distinct language and consider Carpatho-Ruthenian dialects as regional versions of Ukrainian.
The oldest known texts in Ruthenian were written in the 10th century.