The "dyula" have been predominantly Muslim since the 13th century. Many in rural areas combine Islamic beliefs with certain pre-Islamic animistic traditions such as the presence of spirits and use of amulets. "Dyula" communities have a reputation for historically maintaining a high standard of Muslim education. The "dyula" family enterprise based on the "lu" could afford to provide some of its younger men an Islamic education. Thus, an "ulema" (clerical) class known as karamogo emerged, who were educated in the Quran and commentary ("tafsir"), "hadith" (prophetic narrations), and the life of Muhammad. According to the "dyula" clerical tradition, a student received instruction under a single "sheikh" for a duration varying from five to thirty years, and earned his living as a part-time farmer working his teacher's lands. After he completed his studies, a "karamogo" obtained a turban and an "isnad" (teaching license), and either sought further instruction or started his own school in a remote village. A highly educated "karamogo" could become a professional "imam" or "qadi" (judge).