Ryan Skinner has done work on the relationship of music and politics in contemporary Mali. Traditional music The Malinké, Soninke - Sarakole, Dyula and Bambara peoples form the core of Malian culture, but the region of the Mali Empire has been extended far to the north in present-day Mali, where Tuareg and Maure peoples continue a largely nomadic desert culture. In the east Songhay, Bozo and Dogon people predominate, while the Fula people, formerly nomadic cattle-herders, have settled in patches across the nation and are now as often village and city dwelling, as they are over much of West Africa. Historical interethnic relations were facilitated by the Niger River and the country's vast savannahs. The Bambara, Malinké, Sarakole, Dogon and Songhay are traditionally farmers, the Fula, Maur, and Tuareg herders and the Bozo are fishers. In recent years, this linkage has shifted considerably, as ethnic groups seek diverse, nontraditional sources of income. Praise-singers Mali's literary tradition is largely oral, mediated by jalis reciting or singing histories and stories from memory. Amadou Hampâté Bâ, Mali's best-known historian, spent much of his life recording the oral traditions of his own Fula teachers as well as those of Bambara and other Mande neighbors. The jeliw (sing. jeli, fem. jelimusow, French griot) are a caste of professional musicians and orators, sponsored by noble patrons of the horon class and part of the same caste as craftsmen (nyamakala). They recount genealogical information and family events, laud the deeds of their patron's ancestors and praise their patrons themselves, as well as exhorting them to behave morally to ensure the honour of the family name. They also act as dispute mediators. Their position is highly respected and they are often trusted by their patrons with privileged information since the caste system does not allow them to rival nobles. The jeli class is endogamous, so certain surnames are held only by jeliw: these include Kouyaté, Kamissoko, Sissokho, Soumano, Diabaté and Koné. Their repertoire includes several ancient songs of which the oldest may be "Lambang", which praises music. Other songs praise ancient kings and heroes, especially Sunjata Keita ("Sunjata") and Tutu Jara ("Tut Jara"). Lyrics are composed of a scripted refrain (donkili) and an improvised section. Improvised lyrics praise ancestors, and are usually based around a surname. Each surname has an epithet used to glorify its ancient holders, and singers also praise recent and still-living family members. Proverbs are