There are differing explanations as to why this act was instituted, one of which is that Indians' control of land and natural resources around the country was regarded as a serious potential threat to Americans' expansionary and economic goals.
This quickly posed a potentially dangerous security and insurance concern for many enterprising Americans, and the federal government, responsible for protecting its own citizens, was expected to respond with a solution not known before and departing from that previously practiced by the British Empire.
As a consequence, conflict in the Great Plains region was aggravated when settlers began to move into the final remaining land and Native Americans had no place in which to be relocated.
"[9] On the other hand, the statute also declared "no obligation of any treaty lawfully made and ratified with any such Indian nation or tribe prior to March 3, 1871, shall be hereby invalidated or impaired.
Thus, later in 1889, an amendment to the Indian Appropriations Act allowed President Benjamin Harrison to be involved in this historical bill as well, proclaiming unassigned lands were open for settlement under much less stringent rules.