a tribe of North American Indians of Siouan stock. When first met they were living on the Missouri at the mouth of the Heart river. At the beginning of the 19th century they were driven up the Missouri by the Sioux. In 1845, they joined the Gros Ventres and later the Arikaras, and. settled in their present position at Fort Berthold reservation,., North Dakota. The Mandans have always been agricultural; they are noted for their ceremonies, and from the tattooing on face and breast were described in the sign language as "the tattooed people."