Simplify the following text for a Grade 9 native English-speaking person.
Original: The history of Salland goes back to the early Middle Ages , when the four quarters of Oversticht ( Salland , Twente , Land van Vollenhove and Drenthe ) were acquired by the Prince-Bishopric of Utrecht .
Simplified: The history of Salland goes back to the early Middle Ages , when the four quarters of Oversticht ( Salland , Twente , Land van Vollenhove and Drenthe ) came together .