From the California standards on history and social studies:
5.3 Students describe the cooperation and conflict that existed among the American Indians and between the Indian nations and the new settlers.
Competition and cooperation is a prominent theme in the fifth grade. Developmentally, it makes sense. Fifth graders are good at competition. They are also good at cooperation. These are very tangible things to them, which make this type of history pretty appropriate for them to understand.
Now, I know there's a whole bunch of political, unrecorded history on Native Americans and their interactions with Europeans. That's the nature of history - any history, not just of North America. I know I'm interested in those things, but not every fifth grader will be. In teaching, I have to remind myself that I can't teaching it all in one year. There are so many stories that don't get told in the classroom.
Which makes me think one of the purposes is to have students feel it is worthwhile to do the research themselves. Such a simple, straightforward purpose. Why do I forget it so often? And more importantly, how can I remember it more so I can teach better?