In English, Ruthenia is a geographical exonym for a cross-border region of Eastern Europe. It can refer to significantly different and even mutually exclusive areas, dependent on the historical period and subject.
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 CE, "Ruthenia" was used to describe Rus': the wider area occupied by the Ancient Rus' (commonly referred to as Kievan Rus'). This historical territory corresponds to modern Ukraine and Belarus, as well as western Russia, eastern Slovakia and southern Poland. However, the geographical implications of "Ruthenia" and "Russia" began to diverge in meaning as early as the 14th century CE.
In modern usage, Ruthenia usually refers to a region centred on, but not restricted to, Zakarpattia Oblast (the Transcarpathian administrative region) of south-western Ukraine. It is strongly associated with areas inhabited by Rusyn minorities. There is considerable overlap between this usage of "Ruthenia" and a trans-border region also known as Galicia or Halychyna (Halychyna; Rusyn: Галичина; ; , Galitsiya/Galichina; ), which takes in south-western Ukraine, south-eastern Poland and north-eastern Slovakia.