Complex sentence: The former state of Prussia took its name from the Baltic Prussians, although it was led by Germans who had assimilated the Old Prussians and the old Prussian language was extinct by the 17th century.
Split into simpler sentences: The former state of Prussia took its name from the Baltic Prussians, although it was led by Germans who had led to the end of the Old Prussians. The Old Prussian language was extinct by the 17th century.