Regarding belly dance, because it's a hot button of mine, I have to get this off my chest.
Most people in general in that region can dance that way. Men, women, children - it's just how they move when they dance. Traditionally, women would dance for other women to entertain themselves. Same goes for men dancing with men. The movements performed during the dance help to strengthen the pelvic floor muscles and ease pregnancy and childbirth. A friend of mine even went through certain motions while in labor to ease the pain.
There are many traditional reasons for "belly dancing" and many forms of the dance. Some are religious, some are spiritual, people dance to celebrate weddings, fertility, to tell a story and to pass history on to future generations. Rarely is it the oversexualized version that we see here in the west. Yes, it does exist there, but it would be like saying that the only women that dance in the US are strippers.
In my experiences with traditional dances, the amount of clothing worn would surprise most people. I've had costumes that weighed over 35 pounds when it was all thrown into a bag.
A huge part of the western misconception has to do with the Victorian era reports of the dance that were made by men who would only have been exposed to a lesser caliber of dancer and not the respectable women dancing with their families and friends in private homes and celebrations.
Ok, I feel better now.