Why did the plains Indians lose control of the plains?

Why did the plains indians loase controll of the plains?

Indians lost control of the plains due to white settlers. Although there are many causes which could of contributed to the Indians demise, it is hard to determine the most important. Some of these factors i think significant than others.
One reason of why the indians lost controll of the plains was the development of homesteading. Homesteaders would fence of the land which the buffalo used to graze on and the indians used to live on. Once more and more homesteaders became ving and using the land on the Plains, fights began to break out between them and the Indians. Which cut down the Plains Indians land and lost their chance of regaining it back to they way it used to be. Another reason of why the indians lost controll of the plains was the discovery of gold which miners dug for in the black hills, which was part of the plains indians land. This development of the miners broke the for laramie treaty which then led to the miners and plains indians to conflict. Another vital reason for why the plains indians lost control is the development of the railroads (transcontinental railroads). The railroads opened up the west to the homesteaders, ranchers and the buffalo hunters. For the Plains Indians, however, the railroad was disastrous. Their buffalo were decimated by hunters who used the railroad to ship the hides and buffalos bones to the East. As the homesteaders flooded in, the Plains Indians were forced to give up even more land.
A forth reason why the plains indians lost control of their land is because of 'manifest destiny'. White settlers thought that it was their manifest destiny to travel to the west. This was their justification for all of their actions, even treating the indians badly. Because of this manifest destiny more and more settlers traveled to the plains to fufill their manifest destiny, but unfortunatly this led to even more of the plains indians loosing