In the early days of colonization many settlers were subject to shortages of food, disease and attacks from Native Americans. Native Americans were also often at war with neighboring tribes and allied with Europeans in their colonial wars. At the same time however many natives and settlers came to depend on each other. Settlers traded for food and animal pelts, natives for guns, ammunition and other European wares. Natives taught many settlers where, when and how to cultivate corn, beans and squash in the frontier. European missionaries and others felt it was important to "civilize" the Indians and urged them to concentrate on farming and ranching without depending on hunting and gathering.