Simplify the following text for a Grade 7 native English-speaking person.
Original: The antagonism of the rival parties continued , even after Gluck left Paris in 1780 ; and an attempt was afterwards made to inaugurate a new rivalry with Sacchini .
Simplified: The rival parties went on arguing , even after Gluck left Paris in 1780 . Then some people tried to get a new rival for Piccinni : they invited Sacchini to Paris .