I need help recommending some good sources to my friend on how European settlers and the American govt treated indigenous people groups.

For background, my friend was educated in exclusively Christian school/homeschool. He told me he had never even heard about the Trail of Tears in a conversation today. When I asked him about it, his understanding of that subject is limited to the popularized pilgrims and Indians type story. He asked me if I could find some good information on the subject so he could learn more.

I was hoping someone could recommend some good books or articles I could give him on the subject. Thanks!