Whose state was the Grand Duchy of Lithuania?

The late thirteenth and early fourteenth centuries witnessed a dramatic geopolitical change in eastern Europe. While the Mongols took over the eastern and northern parts of the former Kyivan realm, the rest of the region, with the notable exception of Galicia, eventually found itself within the boundaries of the Grand Duchy of Lithuania. That process reached its pinnacle during the rule of Grand Dukes Gediminas (1316–41) and Algirdas (1345–77), whose power extended to most of present-day Belarus, Ukraine, and even some parts of Russia. By the mid-fifteenth century, the ratio of Lithuanian ethnic territories to those settled by Eastern Slavs in the Grand Duchy of Lithuania was 1:12. In the fourteenth century most of the Rurikid princes in the southwestern part of the former Kyivan realm were either deposed or forced to recognize the authority of the Grand Duke of Lithuania. Most scholars assume that the political takeover was largely peaceful, but there are sources that indicate major military confrontations between the Lithuanians and the Rus′. A case in point is the alleged capture of Kyiv by Gediminas, reported in a much later chronicle account. Unfortunately, we have very few sources from the fourteenth century to rely on.

Gediminas was probably the first Lithuanian ruler to call himself Rex Letvinorum et Ruthenorum and refer to his realm as regnum Letuinorum et (multorum) Ruthenorum. His son Algirdas added to his title the Rus′ designation “grand prince” (velykyi kniaz′).