In countries like Mongolia, many people (mainly girls) learn contortion and it is considered a nationally respected art form that holds cultural importance. For hundreds of years contortionists have entertained crowds all over Mongolia. Contortionists usually start practicing from a very early age. In Mongolia the minimum acceptable age is 5, as they believe contortion can cause bone deformities in children under 5 years. Some sports, rhythmic gymnastics for example, demand extreme flexibility but not the hand balancing skills or performance skills of a contortionist.