Who placed the Indians on the reservations?

Answer 1

There is no definitive person who put the Indians on the reservations; Indians were being moved as early as the 1820s. The Permanent Indian Frontier was established in 1834, which was a sort of reservation - the land was reserved for the Indians. Having been broken not only earlier by mountain men etc. going to the Rockies, but then in 1849 by the miners going to California for the Gold Rush. Next was the Fort Laramie Treaty of 1851, which allowed settlers going West passage through the territory. This was broken multiple times, perhaps most notably by the Pikes Peak gold rush in Colorado in 1859. Following this, there was the Fort Laramie Treaty with the Sioux in 1868 following Red Cloud's War over miners going to Montana. My apologies for throwing so much information at you.

This is a very broad generalisation, clearly focused on the Sioux - by far the most interesting tribe - but there were other reservation treaties made with other tribes at various points through the century. The main point, really, was that there were many points at which Indians were forced onto ever smaller reservations. There are three dates above, distributed throughout the century. All treaties, I believe, were managed by the Bureau of Indian Affairs, and enforced by the US Army.

Answer 2

The United States government, specifically through various acts and policies such as the Indian Removal Act and the Indian Appropriations Act, played a significant role in placing Native Americans on reservations. These actions were part of a larger effort to remove Native Americans from their traditional lands and force assimilation into American society.