Hi Nanoussa, hier etwas über Gnawa Musik:
http://www.worldmusicportal.com/Genres/gnawa.htmGnawa
Gnawa is a term used to define both a Moroccan music style and a Muslim religious brotherhood that invokes God and many prophets.  The patron saint of the is Bilal al Habashi, an Ethiopian who was the first African to convert to Islam and Prophet Mohammed's first muezzin (caller to prayer). The Gnawa also recognize and respect all Muslim saints. 
The origin of Gnawa music originally comes from West Africa, south of the Sahara. Over 500 years ago, slavery, conscription and trade brought people from West Africa to North Africa, which was then Morocco, Tunisia, Algeria and Mauritania. 
When they got to the north, they brought their music with them which was called Gnawa. Since these different groups all played the same type of music, they call themselves the Gnawa people. Gnawa song texts contain many references to the privations of exile and slavery. 
Gnawa music is based on pentatonic melodies and the syncopated rhythms  led by the propulsive drive of a bass lute called sintir, metal castanets known as karkabas (also known as k'rkbs and qaraqeb) and chanting. 
The Gnawa are most visible as entertainers. Each afternoon on Jamaa el-Fna, the large entertainment town square in Marrakech, groups of Gnawa perform acrobatic dances to the accompaniment of large side drums (tbel or ganga) and the karkabas. The sound of the drums also rousts any spirits (jnun) that may have settled in the neighborhood. 
Gnawa music is very powerful spiritual music and it is primarily used for healing. The Gnawa carry out trance ceremonies (derdeba) in order to heal people who are very sick. The goal may be to purge an evil spirit that has brought the illness, infertility, stress or some other affliction; or the purpose may be to prolong a positive relationship with a spirit that has brought prosperity, good fortune, or some other baraka (blessing).