When the Europeans arrived they brought with them diseases unknown to the natives. The natives, having no immunity died from diseases that the Europeans thought of as commonplace. They also brought guns, alcohol and horses. The effect of these was to change the way of life for the Native Americans. Horses and guns changed their way of hunting for food. Since the cultural groups had been based on their method of subsistence, changing this changed the groupings. Some major groups moved. Once they started to move fights over territory broke out. Groups, who had had plenty of food, now didn't have enough. Missions were introduced, and Natives were aggressively encouraged to convert to Christianity. Most of the groups had had some form of ancestral worship, and this enforced change in religion altered their culture identity. On top of all of these factors was the Europeans need for land and food. Native groups, because they were nomadic, didn't see land as belonging to one person. The idea that someone could come in, claim a piece of land and ban them from it caused many problems. Wars broke out over the fact that they could no longer hunt or forage for food in places they had always done so. Some of the effects that colonization had were unintentional. No one thought much about immunity to