Original sentence: In the early Middle Ages the consolidation of Baltic lands under Lithuanian supremacy led to the gradual Lithuanization and subsequent assimilation of neighbouring Baltic tribes or their parts, including the Selonians, Jotvingians, Nadruvians and Curonians.On the contrary, a large part of the Grand Duchy of Lithuania remained Ruthenian, since due to a religious, linguistic and cultural dissimilarity there was little assimilation between the  ruling nobility of the pagan Lithuanians and the conquered Orthodox Eastern Slavs
Edited sentence: In the early Middle Ages the consolidation of Baltic lands by the Duchy of Lithuania led to the gradual Lithuanization and subsequent assimilation of neighbouring Baltic tribes or their parts, including the Selonians, Jotvingians, Nadruvians and Curonians who shared religious, cultural, and linguistic similarities.On the contrary, a large part of the Grand Duchy of Lithuania remained Ruthenian, since due to a religious, linguistic and cultural dissimilarity there was less assimilation between the  ruling nobility of the pagan Lithuanians and the conquered Orthodox Eastern Slavs