The Mandans are a tribe Amerindian originating in the area of the North Dakota. They form today part of the Nation Mandan, Hidatsa and Arikara.

With their apogee, Mandans had a prosperous culture based on the Agriculture and the Commerce. Some speculated that Mandans were not really natives, but rather of lost Europeans. It is most probably not the case. However, the theory persists in certain circles. According to medieval manuscripts preserved in the abbeys of Conway and Strat Flur, in 1169, the prince Welsh Madoc decided to be established on these American grounds about which he had intended to speak. It accosted in the current State of Alabama, then set out again with one of the ships to the Wales and returned with ten vessels and three hundred men, went up the the Mississippi, the Ohio, and was folded up finally on the Missouri. Certain historians think that Mandans, Indiens white, with the clear Cheveux and the Yeux gray or blue, which built roomy houses, and which disappeared at the XIXe century, because undoubtedly of their easy assimilation by the Anglo-Saxon population , were the descendants of the men of Madoc.

Lewis and Clark remained among Mandans when they passed in the area, in particular during the winter 1804-1805.

The Variole decimated most of Mandans, and finally forced them to group with the Hidatsa S then the Arikara S to survive. This union gave rise to the Nation Mandan, Hidatsa and Arikara. When the colonists started to arrive at the end of the nineteenth century, they were placed in the reserve of Strong Berthold.