Long before Europeans arrived, American Indian tribes fought each other for land and resources. This caused ongoing rivalries and tensions over hunting territories. When Europeans entered North America, they exacerbated these conflicts by trading weapons and horses to some tribes, giving them strategic advantages over others. This allowed certain tribes like the Iroquois, Ojibwa, and Lakota to push neighboring tribes off desired lands through periods of prolonged warfare. European involvement thus intensified and expanded the scale of existing land disputes between American Indian groups.