Simplify the following text for a Grade 10 native English-speaking person.
Original: The biggest green area in ChojnÃ w is small forest Park Piastowski ( Piast 's Park ) , named after Piast dynasty as part of Communist anti-German propaganda .
Simplified: The biggest green area in ChojnÃ w is small forest Park Piastowski ( Piast 's Park ) , named after the Polish Piast dynasty .