What is the author's tone in the nonfiction book, An Indigenous Peoples’ History of the United States?

The book’s tone is measured and direct, and all of the book’s claims are substantiated with historical facts and evidence. The book exposits upon many grave injustices throughout American history, but the tone never becomes overtly tragic or emotional. Instead, the text allows historical facts and information speak for themselves, thereby illustrating the tragedy of this history without distraction or embellishment.