According to George Catlin, the Sioux were the largest of All the Native American tribes. This is due to them once occupying the Ohio Valley and intermarrying with the Adena mound builders, who were in some cased 8 or 9 feet in height.
History of Fremont County, Iowa 1881
In 1875 a huge human skeleton was unearthed at a brick-yard about one mile east of Hamburg at a depth of fourteen feet from the surface of the earth. The bones were for the most part in an advanced state of decay but the teeth were well preserved. The remains are believed to be those of a giant at least eight feet in height. The teeth were worn down almost to the jaw-bone, which fact indicated that the "mighty men of renown" must have lived in the days mentioned by the old Indians who formerly lived in the vicinity of Hamburg. "Long ago," said they, "our fathers used to ride across the Missouri river here on their ponies, for the water was very shallow. The eastern margin of the river then was at the foot of the high bluff (at Hamburg) and the river itself was very wide. But there were so many bad men among our fathers in those days and they engaged in so many wars that the Great Spirit cursed the waters of the river (the Missouri) and caused it to run in a narrower and deeper channel, so that the tribes, could not cross and fight and kill one another. After that our fathers lived till their feet were worn off with walking and their teeth worn down with eating." Many other bones of extinct giant animals and men have been found in the same locality where the skeleton before was described."