Simplify the following text for a Grade 10 native English-speaking person.
Original: His biggest commercial success came with the action adventure film ( co-starring Rachel Weisz ) The Mummy ( 1999 ) and its sequel The Mummy Returns ( 2001 ) , both of which were hugely successful at the box office .
Simplified: His best success was with the film ( which also had Rachel Weisz as an actor ) called The Mummy in ( 1999 ) and its sequel The Mummy Returns ( 2001 ) , both of which were very successful .