Белая Русь
The 16th century chronicler Alexander Guagnini's book "Sarmatiae Europeae descriptio" wrote that Rus' was divided in three parts. The first part, under the rule of the Moscovite Grand Duke, was called "White Russia". The second one, under the rule of Polish king, was called "Black Russia". And the rest was "Red Ruthenia". He also said Moscow was the center of White Russia and Russian metropolitanate, and that Grand Duke of Moscow was called the "White Czar", especially by his subjects.