when europeans first came to north amarica, why did they bring widesread changes amoung the amarican indians?

Leaders formed alliances with Native American nations to fight foreign powers. Some famous alliances were formed during the French and Indian War of 1754–1763. The English allied with the Iroquois Confederacy, while the Algonquian-speaking tribes joined forces with the French and the Spanish. The English won the war, and claimed all of the land east of the Mississippi River. The English-allied Native Americans were given part of that land, which they hoped would end European expansion—but unfortunately only delayed it. Europeans continued to enter the country following the French and Indian War, and they continued their aggression against Native Americans. Another consequence of allying with Europeans was that Native Americans were often fighting neighboring tribes. This caused rifts that kept some Native American tribes from working together to stop European takeover.