Belly dance is the western name for Raqs Sharki a type of middle eastern dance. It is a dance that is traditionally solo form and is improved with the name it referring to the torso isolations. When your hips are moving, you have a natural shimmy to your midsection refers to the western called name. Every region in the middle east has different look to the dance and costumes can vary in style. The dance has boomed in the 2000s and has grown to global portions of popularity for fitness and as an art.
Learn more about this dance on Wikipedia