Which religion is practiced by almost all Mauritanians?

Almost all Mauritanians are Sunni Muslim.1

While the country's constitution designates Islam as the official state religion, it also guarantees freedom of conscience and religious liberty to all citizens. The declaration of Mauritania as an Islamic republic at the time of its independence was intended to help unite its diverse population under a common faith. Additionally, many Mauritanians are adherents of Sufi brotherhoods, specifically the Qādiriyyah and Tijāniyyah orders.21