Why did the Native American population decline when white settlers came west?

The Native American population declined significantly with the arrival of white settlers due to a combination of factors, including the spread of diseases such as smallpox, to which Indigenous peoples had no immunity. Violent conflicts and wars over land and resources, along with forced relocations and broken treaties, further devastated their communities. Additionally, the disruption of traditional ways of life and the introduction of new economic systems contributed to social and cultural disintegration. These factors collectively led to a dramatic decrease in the Native American population during westward expansion.