Via Univ. of Oklahoma College of Law
"This collection offers detailed contemporaneous documentation of political, military, and governmental activities related to indigenous peoples of the continental United States and Alaskan territory during the 19th century."

"The Native Health Database contains bibliographic information and abstracts of health-related articles, reports, surveys, and other resource documents pertaining to the health and health care of American Indians, Alaska Natives, and Canadian First Nations."
Partially govinfo - its a bit complicated (see the History tab).

"This database includes agreements between tribal nations and the United States (1778-1886) published in the 1904 work “Indian Affairs: Laws and Treaties” (Volume II), compiled and edited by Charles J. Kappler. As you view the treaties in this database, editorial margin notes are included. Links to Kappler’s original text and digitized treaties held at the National Archives can also be found throughout the site. Finally, a recently updated, comprehensive index complements this work."