Simplify the following text for a Grade 5 native English-speaking person.
Original: Saxe-Eisenach assumed its final shape in 1672 , following the death of Frederick William III of Saxe-Altenburg and the partition of his lands .
Simplified: Saxe-Eisenach changed again in 1672 . Frederick William III of Saxe-Altenburg died and his lands were split .