Between 1885 and 1935, the U.S. Government required that Native Americans participate in an annual census.
The census rolls provide additional government documents that can prove kinship and ethnicity for your ancestors. Look for the individuals in your family tree and track their family connections to parents, siblings, spouses, and children as you fill in your family group sheets and pedigree charts.
The original documents are stored and preserved at the National Archives. Links to digital and print versions are provided below.