How did the Indians obtain their superior firepower?
From gun runners.
No background checks.
In Bourke’s book ON THE BORDER WITH CROOK he mentions how before the battles, traders were selling tube magazine rifles to the tribesmen.
He says once the warriors were armed with such weapons they became “surly”. It would be considered the a-s-s-ault rifle of the day, yet no one called for banning them.
When Crook attacked several of the Cheyenne villages, and burned them, the camps actually exploded, there was so much ammo and gunpowder there.