Simplify the following text for a Grade 9 native English-speaking person.
Original: In 1472 , Bavaria 's first university was founded in Ingolstadt . The Bavarian Reinheitsgebot , a regulation about the purity of beer , was started there in 1516 .
Simplified: Ingolstadt was the city where William IV , Duke of Bavaria wrote and signed the Bavarian Reinheitsgebot in 1516 .