Original sentence: Even when some localities received the appointed Gediminid leaders, the  Lithuanian higher nobility in the Ruthenian lands largely embraced the Slavic customs and Orthodox Christianity and became indistinguishable from a larger Ruthenian nobility resulting in the two cultures merging to the extent that much of the upper class of the Grand Duchy called themselves Lithuanians gente Rutenus natione Lituanus
Edited sentence: Even when some localities received the appointed Gediminid leaders, the  Lithuanian higher nobility in the Ruthenian lands largely embraced the Slavic customs and Orthodox Christianity and became indistinguishable from a larger Ruthenian nobility resulting in the two cultures merging to the extent that much of the upper class of Ruthenians merged into Lithuanian nobility and began to call themselves Lithuanians gente Rutenus natione Lituanus