"We don't need no stinking Lt. Dunbar"
There a line from some famous movie saying "Badges? We Don't need no stinking badges!"
Historically speaking, there is a big lie in Dances With Wolves (1990), somewhat similar to the big lie in The Comancheros (1961). The big lie in the fictional plot of The Comanderos is that in 1843 a secret society, the title Comancheros, was stirring up trouble between the Comanches and the Texas. But real history "didn't need no stinking Comancheros" to still up trouble between the Comanches and the Texans. Even though their homes were separated by hundreds of miles of empty land, it wasn't far enough, and the Comanches and the Texans were both such bad neighbors that they became bitter enemies.
And similarly the Sioux and the USA "didn't need no stinking Lt. Dunbar" to be the cause of trouble between, them, not in 1863 or 1864. At the end of the movie Dunbar leaves the Sioux group he stayed with, hoping to avoid endangering them. Like that would work in real life!
Originally there were seven groups of Sioux, four tribes of Santee Sioux or Nakota, two tribes of Yankton Sioux or Dakota, and one tribe of Teton Sioux or Lakota. In the 1700s the Teton moved from the woodlands onto the plains, adopted horses, and flourished, eventually becoming so numerous than by 1850 they split into seven tribes of Teton Sioux, the famous plains Sioux of the Wild West.
What of the Sioux tribes who remained in Minnesota? The movie Flaming Frontier (1958) says that during the Civil War they revolted but the hero Capt. Houston managed to persuade Chief Little Crow to make peace at the end. According to some reviews the uprising was very small scale as depicted in that very low budget film.
https://www.imdb.com/title/tt0051619/reviews/?ref_=tt_urv_sm
In real life, the Santee Sioux grew discontented, and in 1862 many them fought a very brutal uprising, slaughtering hundreds of men, women and children. Tens of thousands of settlers fled from their homes.
General Henry Hastings Sibley defeated the Santee Sioux at the Battle of Wood Lake on September 23, 1862. Little Crow fled and was killed in a shootout with a settler on July 3, 1863. Sibley negotiated for the surrender of Santee Sioux and the release of their many prisoners. Sibley formed a military commission in 1862 to try Sioux warriors.
As I wrote in my answer at https://www.quora.com/What-if-a-Native-American-committed-a-crime-and-said-to-the-police-court-I-m-not-bound-by-your-laws-this-is-my-land-not-yours :
"...The military commission tried 393 persons, convicted 323, and sentenced 303 to be hanged. President Lincoln reviewed the sentences and reduced most of them, letting 39 death sentences stand. One got a last minute reprieve and 38 were hanged on December 16, 1862 at Mankato, Minnesota."
Many Minnesotans were bitterly disappointed that only 38 Sioux were hanged and wanted to exterminate all Sioux in Minnesota. Instead the Santee Sioux were exiled to reservations in Dakota and Nebraska. Minnesota did put a price on the head of any Sioux found in Minnesota.
And if the Sioux thought that would be the end of the matter, they were very much mistaken.
Continued.