Simplify the following text for a Grade 7 native English-speaking person.
Original: The Tridentine Mass is the form of the Roman Rite Mass contained in the typical editions of the Roman Missal that were published from 1570 to 1962 . It was the most widely celebrated Mass liturgy in the world until the introduction of the Mass of Paul VI in December 1969 .
Simplified: Tridentine Mass is the name given to a Roman-rite catholic mass , as it was common before 1969 .