A semi-noble strata of the Tuareg people has been the endogamous religious clerics, the "marabouts" (Tuareg: "Ineslemen", a loan word that means Muslim in Arabic). After the adoption of Islam, they became integral to the Tuareg social structure. According to Norris, this strata of Muslim clerics has been a sacredotal caste, which propagated Islam in North Africa and the Sahel between the 7th and the 17th centuries. Adherence to the faith was initially centered around this caste, but later spread to the wider Tuareg community. The marabouts have traditionally been the judges ("qadi") and religious leaders ("imam") of a Tuareg community.