What happened to many Native Americans as Americans pushed further west into Indian territory?

Indian removal was a forced migration in the 19th century whereby Native Americans were forced by the United States government to leave their ancestral homelands in the eastern United States to lands west of the Mississippi River, specifically to a designated Indian Territory (roughly, modern Oklahoma).[1][2][3] The Indian Removal Act, the key law that forced the removal of the Indians, was signed by Andrew Jackson in 1830. Jackson took a hard line on Indian removal, but the law was put into effect primarily under the Martin van Buren administration.[4][5]

Indian removal was a consequence of actions first by European settlers to North America in the colonial period, then by the United States government and its citizens until the mid-20th century.[6][7] The policy traced its direct origins to the administration of James Monroe, though it addressed conflicts between European Americans and Native Americans that had been occurring since the 17th century, and were escalating into the early 19th century as white settlers were continually pushing westward.

Explanation:

What happened to many Native Americans as Americans pushed further west into Indian territory?