"Indians are no longer important in American History"

In Elementary American History and Government, I found that the authors, James A. Woodburn and T.F. Morgan, were extremely biased. Throughout the reading we were given ("The Indians"), I found many of the things they said very appalling. For example, in the section titled "Warfare", the first sentence I found obnoxiously unknowledgeable. It reads: "The Indians were constantly at war, either among themselves or with white men." This statement convinces me that either the extent of the authors' knowledge is extremely limited, or that their ignorance is great. The fact that they stated that the Indians were are war among themselves made me angry; did they not understand that there are different tribes of the Native Americans, just like there are different countries of Europeans? But the topic I found the most confounding was the section titled "Religion." They stated that "The Indians were not very religious, but he did think that the souls of the dead went to a far-off 'happy hunting ground.'" I was simply taken aback by that sentence. The complete disregard for Indian culture disgusts me. What does "not very religious" mean? That they were not Christian? And "a far-off 'happy hunting ground.'" First off, not all Indian tribes hunted. You cannot generalize based on one source; which I would actually very much like to see a list of the sources these authors used. Yes, the book was written in 1914, but that does not mean anything. This was quite possibly the most biased article I have ever read.