（初めに右欄で英語を１つ選び、続いて選択肢から１つを選んでください。やり直すときは、英語を選び直すことから始めてください。右の［単語帳］を参考にすることもできます。）The United States began to expand west during the middle eighteen hundreds. People settled in the great open areas of the Dakotas, Utah, Wyoming, and California. The movement forced the nation to deal with great tribes of Native American Indians. The Indians had lived in the western territories for hundreds of years.
Settlers and cattle ranchers pushed the Indians out of their homelands. The result was a series of wars between the tribes and the federal government.
At first, the United States government had just one policy to deal with the Indians. It was brutal. Whenever white men wanted Indian land, the tribes were pushed farther west. If the Indians protested, or tried to defend their land, they were destroyed with crushing force.
By the middle eighteen-hundreds, almost all the eastern Indians had been moved west of the Mississippi River. They were given land in Indian territory in what is now the state of Oklahoma. The government described these Indians as "civilized." This meant they were too weak to cause more trouble. Many agreed to follow the ways of the white men.
The Indians of the western grasslands were different. They refused to give up their way of life. These plains Indians were always on the move, because they hunted buffalo -- the American bison. They followed great groups of the animals across the grassy plains. At that time, there were millions of these animals in the American west.