As the pioneers crossed the western plains to California and Oregon, the Indians they encountered were at first helpful and friendly. The Indians guided pioneer wagon trains through mountain passes and across rivers. The pioneers traded with them for horses and food. But as had happened in Kentucky, the Indians became resentful as the great numbers of settlers began to overrun their lands. The pioneers killed their buffalo for food. Cattle overgrazed the grass and drank up the watering holes. Farmers took Indian land and cut down the trees. Many Indians came to believe that they must fight these invaders or face the total annihilation of their way of life. Some tribes charged tolls for passing through Indian territory. The pioneers thought the Indians had no right to charge these tolls and often refused to pay. The Indians would then steal the settlers'...