Black Ruthenia (Latin: Ruthenia Nigra), Black Rus' (Belarusian: Чорная Русь / Čornaja Ruś, Polish: Ruś Czarna, Lithuanian: Juodoji Rusija) identified a historical region around Navahrudak (Nowogródek), in the western part of present-day Belarus on the upper reaches of the Neman River. Besides Navahrudak, other important cities of the Black Ruthenian region included Hrodna (Grodno), Słonim (Słonim), Vaŭkavysk (Wołkowysk) and Niaśviž (Nieśwież).
This article needs additional citations for verification. (March 2008)
The convention of distinguishing different regions of the Ruś by colours was first used in Western European sources circa 1360 by Heinrich von Mügeln, referring to the Black and Red Ruthenia (placing them in modern Ukraine). Some researchers claim that this color naming convention was influenced by the Mongol invaders, who used them for the cardinal directions. During the Second Partition of Poland in 1793, the eastern part around Słuck was annexed by the Russian Empire and incorporated into the Minsk Governorate. The western part followed in the Third Partition of 1795 and was administered within the Grodno Governorate. Early Ruthenian sources do not use the term "Black Ruś", the name "Black Ruthenia" appears primarily in historical writings from the 18th century.