Why were the native Americans moved from their land?
To put it simply, the Native Americans were moved from their land because the white settlers from Europe wanted it. They were able to overpower the Native Americans and force them to give up the land. Later in American history, the United States government allotted land for the Native Americans in the form of reservations. Conditions on the reservations have been very poor historically and continue to be so.
The native Americans were continually moved westward because the new colonists desired the land that they were living on, and as the population of the colonists (and later Americans) grew they needed more and more land. As such, politicians, and citizens alike requested more and more land, which they killed many Native Americans over.