A polygon because it is closed.
The act authorized the president to grant Indian tribes unsettled western prairie land in exchange for their desirable territories within state borders (especially in the Southeast), from which the tribes would be removed.
Explanation:
Soldiers of the Soviet Union and the United States did not do battle directly during the Cold War. But the two superpowers continually antagonized each other through political maneuvering, military coalitions, espionage, propaganda, arms buildups, economic aid, and proxy wars between other nations.
This naturally led to the diffusion of multiple inventions, both those of the Mongols and those ideas the Mongols usurped from cultures they conquered. While the Mongols profited from the trade of silk and tea from China to Europe, they also spread the Chinese inventions of printing and paper.
