In winning the Mexican War, the United States achieved its primary goal of

The war officially ended with the February 2, 1848, signing in Mexico of the Treaty of Guadalupe Hidalgo. The treaty added an additional 525,000 square miles to United States territory, including the land that makes up all or parts of present-day Arizona, California, Colorado, Nevada, New Mexico, Utah and Wyoming.

as general terms,  indian territory,  the indian territories, or  indian country  describe an evolving land area set aside by the  united states government  for the relocation of  native americans  who held  aboriginal title  to their land. in general, the tribes ceded land they occupied in exchange for  land grants  in 1803. the concept of an indian territory was an outcome of the 18th- and 19th-century policy of  indian removal. after the  civil war(1861–1865), the policy of the government was one of  assimilation.