Simplify the following text for a Grade 8 native English-speaking person.
Original: Ganggangsullae ( Hangul : ê ê ì ë ) is a 5,000-year-old Korean dance that was first used to bring about a bountiful harvest and has developed into a cultural symbol for Korea .
Simplified: Ganggangsullae ( Hangul : ê ê ì ë ) is a 5,000-year-old traditional Korean dance . It was first used to bring a good harvest and has become a cultural symbol for Korea .