text: In 1825 the Mandans signed a peace treaty with the leaders of the Atkinson-O'Fallon Expedition. The treaty required that the Mandans recognize the supremacy of the United States, admit that they reside on United States territory, and relinquish all control and regulation of trade to the United States. The Mandan and the United States Army never met in open warfare.
  In 1832, artist George Catlin visited the Mandan near Fort Clark. Catlin painted and drew scenes of Mandan life as well as portraits of chiefs, including Four Bears or Ma-to-toh-pe. His skill at rendering so impressed Four Bears that he invited Catlin as the first man of European descent to be allowed to watch the sacred annual Okipa ceremony. During the winter months of 1833 and 1834, Prince Maximilian of Wied-Neuwied and Swiss artist Karl Bodmer stayed with the Mandan.
  Speculation about pre-Columbian European contact
  18th-century reports about characteristics of Mandan lodges, religion and occasional physical features among tribal members, such as blue and grey eyes along with lighter hair coloring, stirred speculation about the possibility of pre-Columbian European contact. Catlin believed the Mandan were the "Welsh Indians" of folklore, descendants of Prince Madoc and his followers who had emigrated to America from Wales in about 1170. This view was popular at the time but has since been disputed by the bulk of scholarship.