Backgrounds】 United States territorial expansion took place at the Indians expanse,and the result was removal of the great Native American nations lands west of the Mississippi. The population of other groups in the US was increasing the American Indian population was shrinking. The assimilation of Native American through education and Christianity had been an explicit goal of the white man.4 Copyright © 2012 Andy Guo. All rights reserved。 【 Backgrounds 】 l United States territorial expansion took place at the Indians 'expanse, and the result was removal of the great Native American nations lands west of the Mississippi. l The population of other groups in the US was increasing ,the American Indian population was shrinking. l The assimilation of Native American through education and Christianity had been an explicit goal of the white man