The American Indian Wars, or Indian Wars, were the multiple conflicts between American settlers or the United States government and the native peoples of North America from the time of earliest colonial settlement until 1924. In some cases, wars resulted from conflicts and competition for resources between the European colonists and Native Americans. There was population pressure as settlers expanded their territory, generally pushing indigenous people northward and westward. Warfare and raiding also took place as a result of wars between European powers; in North America, these enlisted their Native American allies to help them conduct warfare against each other's settlements. Many conflicts were local, involving disputes over land use, and some entailed cycles of reprisal. Particularly in later years, conflicts were spurred by ideologies such as Manifest Destiny, which held that the United States was destined to expand from coast to coast on the North American continent. In the 1830s, the United States had a policy of Indian removal east of the Mississippi River, which was a planned, large-scale removal of indigenous peoples from the areas where Europeans were settling. Particularly in the years leading up to Congressional passage of the related act, there was armed conflict between settlers and Native Americans; some removal was achieved through sale or exchange of territory through treaties.