Except where a great deal of acculturation had already occurred, it has been very difficult to examine the demographic characteristics of any American Indian society in detail. Early ethnographic studies were primarily concerned with material and non-material culture of the pre-contact period and paid little attention to demographic features. In part, this was due to the virtual impossibility of obtaining accurate information about a period often several decades in the past, and in part because the importance of such data was not realized until comparatively recently. In recent years there has been a rapid increase in the number of studies which examine past demographic features. Most of this research has dealt with groups in western Europe and the United States, since records which reveal demographic data are most readily available for these areas. Few if any of these studies have dealt with American Indians.