Original sentence: But for decades to come, the southern borderland was annually pillaged by the Nogai Horde and the Crimean Khanate, who took local inhabitants with them as slaves.Expanding to the northwest toward the Baltic Sea proved to be much more difficult.The period includes the upheavals of the transition from the Rurik to the Romanov dynasties, drawn-out military conflict with the Polish-Lithuanian Commonwealth as well as the Russian conquest of Siberia, leading up to the 42-year reign of Peter the Great, who ascended in 1682 and transformed the Tsardom into a major European power, after a military victory over Sweden and Poland implemented substantial reforms and proclaimed the Russian Empire () in 1721, making it a recognized power in Europe
Edited sentence: But for decades to come, the Southern borderland was annually pillaged by the Nogai Horde and the Crimean Khanate, who took local inhabitants with them as slaves.Expanding to the Northwest toward the Baltic Sea proved to be much more difficult.The period includes the upheavals of the transition from the Rurik to the Romanov dynasties, drawn-out military conflict with the Polish-Lithuanian Commonwealth as well as the Russian conquest of Siberia, leading up to the 42-year reign of Peter the Great, who ascended in 1682 and transformed the Tsardom into a major European-like power, after a military victory over Sweden and Poland implemented substantial reforms and proclaimed the Russian Empire () in 1721, making it a recognized power in Europe