The name ''Belarus'' is closely related with the term ''Belaya Rus'', i.e., ''White Rus'''. There are several claims to the origin of the name ''White Rus''. An ethno-religious theory suggests that the name used to describe the part of old Ruthenian lands within the Grand Duchy of Lithuania that had been populated mostly by Slavs who had been Christianized early, as opposed to Black Ruthenia, which was predominantly inhabited by pagan Balts. An alternative explanation for the name comments on the white clothing worn by the local Slavic population. A third theory suggests that the old Rus' lands that were not conquered by the Tatars (i.e., Polotsk, Vitebsk and Mogilev) had been referred to as ''White Rus'''. A fourth theory suggests that the color white was associated with the west, and Belarus was the western part of Rus in the 9th to 13th centuries.