In post-civil war america, indians surrendered their lands only when they a. chose to migrate farther west. b. received solemn promises from the government that they would be left

In post-civil war america, Indians surrendered their lands only when they received solemn promises from the government that they would be left alone and provided with supplies on the remaining land. Unfortunately the agreement was not a written agreement, so the Americans did not keep their end of the agreement and they ended up taking Indian's land anyway due to the resources available and their belief in manifest destiny.

B. received solemn promises from the government that they would be left alone

After the Civil War new western lands were opened up but still needed to be cleared of Native American tribes.

Legislation like the Homestead Act brought new settlers to the West following the Civil War. New agreements needed to be made with the tribes still living in large concentrations in the West, such as the Sioux. Many of the tribes agreed to give up lands in exchange for promises to set reservation sites which would not be taken away or controlled by the US government. Reservations had to be sovereign allowing the tribes to run the land as they saw fit.