“The Sioux (at least on the plains). That’s why the Crow and the Blackfeet allied with the U.S. Army.”
The Blackfeet were a branch of the Lakota (or Teton) Sioux. The Crows (Absaroka) were not Sioux at all. The Crows hated the Sioux, and many Crows became scouts for the US Army. No one much liked the Blackfeet, except the Gros Ventre, with whom they were neighbors.
***The Crows hated the Sioux, and many Crows became scouts for the US Army.****
What a difference a few months can make in friends and enemies. After Little Big Horn, Gen Crook and Mackenzie attacked a Cheyenne village that had been at the battle. The survivors fled to the band of Crazy Horse who basically told them to “Hit the road!”
With no place to go and freezing weather, that band threw themselves on the mercy of Gen Crook and said they would be willing to scout for him AGAINST CRAZY HORSE!
Today those same tribes try to say the Cheyenne were welcomed by Crazy Horse. So why did they become scouts against Crazy Horse?
In the book ON THE BORDER WITH CROOK by Bourke it tells which Cheyennes became scouts for Gen Crook.