Sutaio Indians (singular, Sŭ´tai; the several attempted Cheyenne etymologies are of doubtful value, as the word is probably not of Cheyenne origin). An Algonquian tribe, residing in the 18th century according to tradition about James river, South Dakota, who were at war with the Cheyenne, their eastern neighbors to whom they were closely related linguistically.  The two tribes finally formed an alliance and crossed the Missouri together to the west, the Sutaio leading the advance.  The Sutaio rapidly declined but kept their separate identity until about the year 1850, when they were absorbed by the Cheyenne.  They exist now only as a division of that tribe.  They are probably identical with the Staitan of Lewis and Clark.