The Kela version includes a written document called a "tariku". This intersection of written and oral history is unique to Mande culture. The epic is typically performed in two ways: one is intended for teaching or rehearsing, and the other is more official, intended to convey the important information to a large audience. Part of the teaching performance involves the presenting of gifts from clans involved in the epic. The official version can use a musical instrument; it does not allow audience interruptions. Different Mande clans play different instruments in their performances of the epic. The Kandasi also started a school for oral history. The Mande people have made many historical chronicles, many undiscovered and many not paid attention to. Mahmud Kati was the Uncle of the author of the Tarikh al-Fattash who is only known as Ibn al-Mukhtar(son of the chosen). Ibn al-Mukhtar heavily from the writings of his Grandfather Mahmud Kati whose works has never been published or haven't been discovered. Most of the Mandé groups in the westernmost part of West Africa have been predominantly Muslim as early as the 13th century, with others like the Bambara being Islamized as late as the 19th century. Traditional beliefs such as initiation groups like Chiwara, Dwo, and beliefs in the power of Juju remain among Muslim Manden. Many smaller Manden groups such as the Bobo retain pre-Islamic belief systems in their entirety. According to oral histories, the Mande, in particular the Soninke, contributed to the Islamization of non-Mande Gur groups at the edge of the Sahel in West Africa through trade and settlement. Much Mandé art is in the form of jewelry and carvings. The masks associated with the fraternal and sorority associations of the Marka and the Mendé are probably the best-known, and finely crafted in the region. The Mandé also produce beautifully weaved fabrics which are popular throughout western Africa, and gold and silver necklaces, bracelets, armlets, and earrings. The bells on the necklaces are of the type believed capable of being heard by spirits, ringing in both worlds, that of the ancestors and the living. Mandé hunters often wear a single bell that can be easily silenced when stealth is necessary. Women, on the other hand, often wear multiple bells, referring to concepts of community, since the bells ring harmoniously together. The best known traditional Mandé music is played on the kora, a stringed instrument with 21 or more strings, and it is performed by families of musicians known as "Jeliw" (sing.