Oral history was and still is of great value to North American Indigenous people. In many cultures the elders were revered as historians. The concept of time may be illustrated in a linear fashion. The concept of time may be illustrated in a cyclical fashion. It is important to keep in mind that these conclusions were usually made by people living in another time and place, and having a different set of values and perspectives.
Historians often use information that other historians have written.
In this way, biases and misunderstandings may be perpetuated, and various interpretations may occur. Authors, no matter how hard they try to be unbiased, write within the contexts of their own values, beliefs and perspectives. New information about the past is very slow to find its way into historical publications. Most of the publications about America's Indigenous peoples have been written from a Eurocentric perspective. The points of view of Indigenous peoples may be quite different from a Eurocentric perspective.