The pioneers usurped the sacred domains and hunting areas of Native Americans and scared away Buffalo herds which were between 30M and 60 Millions before European settlers arrived, and through massive and fatuous slaughter, fewer than 1,000 left.
And although sometimes they traded, and some peaceful encounters occurred, where Natives shared knowledge about how to handle bears and topography information, most tribes were dislodged through violence or diseases. Thereby (the 4th one): "the pioneers settled on the open plains, scaring away buffalo herds and..."