Mauritania is culturally and politically part of the Arab world: it is a member of the Arab League and Arabic is the sole official language. Reflecting its colonial heritage, French is widely spoken and serves as a ''lingua franca''. The official religion is Islam, and almost all inhabitants are Sunni Muslims. Despite its prevailing Arab identity, Mauritanian society is multiethnic: the Bidhan, or so-called "white moors", make up 30 percent of the population, while the Haratin, or so-called "black moors", comprise 40 percent. Both groups reflect a fusion of Arab-Berber ethnicity, language, and culture. The remaining 30 percent of the population is made up of various sub-Saharan ethnic groups. 