Original sentence: In the 13th century, the state was badly affected by a Mongol invasion, and eventually parts of Ruthenia were swallowed up by the Grand Duchy of Lithuania
Edited sentence: In the 13th century, the state was badly affected by a Mongol invasion, and eventually parts of Rus' and Samogitia were swallowed up by the Grand Duchy of Lithuania.The core lands of the duchy comprised the Belarusian territories that included the modern-day city of Navahradak as the first capital