The Mandan had a vague tradition of emigration from the eastern part of the country, and Lewis and Clark, Prince Maximilian, and others found traces of Mandan house-structures at various points along the Missouri; thus they appear to have ascended that stream before the advent of the ȼegiha. During the historical period their movements were limited; they were first visited in the upper Missouri country by Sieur de la Verendrye in 1738. About 1750 they established two villages on the eastern side and seven on the western side of the Missouri, near the mouth of Heart river. Here they were assailed by the Asiniboin and Dakota and attacked by smallpox, and were greatly reduced; the two eastern villages consolidated, and the people migrated up the Missouri to a point 1,430 miles above its mouth (as subsequently determined by Lewis and Clark); the seven villages were soon reduced to five, and these people also ascended the river and formed two villages in the Arikara country, near the Mandan of the eastern side, where they remained until about 1766, when they also consolidated. Thus the once powerful and populous tribe was reduced to two villages which, in 1804, were found by Lewis and Clark on opposite banks of the Missouri, about 4 miles below Knife river. Here for a time the tribe waxed and promised to regain the early prestige, reaching a population of 1,600 in 1837; but in that year they were again attacked by smallpox and almost annihilated, the survivors numbering only 31 according to one account, or 125 to 145 according to others. After this visitation they united in one village. When the Hidatsa removed from Knife river in 1845, some of the Mandan accompanied them, and others followed at intervals as late as 1858, when only a few still remained at their old home. In 1872 a reservation was set apart for the Hidatsa and Arikara and the survivors of the Mandan on Missouri and Yellowstone rivers in Dakota and Montana, but in 1886 the reservation was reduced. According to the census returns, the Mandan numbered 252 in 1890.
