Page "Ukrainian language" Paragraph 4

Soviet scholars set the divergence between Ukrainian and Russian only at later time periods ( 14th through 16th centuries ).

According to this view, Old East Slavic diverged into Belarusian and Ukrainian to the west ( collectively, the Ruthenian language of the 15th to 18th centuries ), and Old Russian to the north-east, after the political boundaries of Kievan Rus ' were redrawn in the 14th century.

During the time of the incorporation of Ruthenia ( Ukraine and Belarus ) into the Polish – Lithuanian Commonwealth, Ukrainian and Belarusian diverged into identifiably separate languages.