Ruthenia
Ruthenia is a proper geographical exonym for Kievan Rus. It was applied to the area where Ruthenians lived.
The word "Ruthenia" originated as a Latin rendering of the region and people known originally as "Rus" – the same root word as Russia. In European manuscripts dating from the 13th century, "Ruthenia" was used to describe Rus': the wider area occupied by the Ancient Rus' (commonly referred to as Kievan Rus'). After of occupation of the Ruthenian Kingdom (Kingdom of Galicia-Volhynia) by the Kingdom of Poland, the territory was converted into the Ruthenian Voivodeship which existed until the 18th century.
With appearance of ethnonym Ukrainians in the 19th century, the use of "Ruthenia" became less common. Residents of Transcarpathia continue to use the Slavic variation of it as the Subcarpathian Rus and thus regard themselves as Rusyns (Ruthenians).
Late Middle Ages
By the 15th century two major states claimed their Rus' ancestry: the Muscovy and the Polish–Lithuanian Commonwealth. Natives used different forms of the name Rus' for their country, and some of these forms also passed into Latin and English.