Simplify the following text for a Grade 6 native English-speaking person.
Original: The Mummy : Tomb of the Dragon Emperor is a 2008 American action adventure film that follows a sequel to The Mummy ( 1999 ) and The Mummy Returns ( 2001 ) .
Simplified: The Mummy : Tomb of the Dragon Emperor is a 2008 American adventure movie . It is a sequel to The Mummy and The Mummy Returns .