What do you think of my introductory paragraph?

How were the lives of the Plains Indians in the second half of the nineteenth century affected by technological developments and government actions?

The Plains Indians were a rich and varied people occuping what is now considered the Midwest. It was thought that their existence in their region would be permanently safeguarded from any encroachment. However, as railroads, mining, cattle, and government intervention ensued, the Plains Indians found themselves unable to maintain their traditional lifestyle.