Everything changed with the unstoppable European migration waves of the British, French, Scandinavians, Germans, aided by missionaries from different congregations. They appropriated increasingly vast lands, the native peoples left pushing one another towards the inland. Bows and arrows, spears and clubs were of no use against the “fire sticks” (rifles). The European companies used to buy from the Indians the skins of beavers, first, and bisons, then, in exchange for guns, horses and, sadly, spirits.
Weapons and horses gave them extreme mobility, as well as the possibility to settle over millions of miles of pristine land, absolutely unsuited for cultivation: it was a radical, irreversible break.
They were hoping that the white men would never come to those inhospitable lands. It was a short-lived illusion, though. When Washington and the trading companies no longer needed to buy from them, they began the slaughter of bisons to starve Natives to death: by 1870, of the over 40-45 million bisons, only a few hundred were still alive. This policy of annihilation and systematic internment was treacherous. The surviving natives had no choice but to take refuge in the myths and legends of the dead.