Dear Mr. Stamper,
Thank you for posting your request on History Hub!
We searched the National Archives Catalog and located a series titled the Rocky Boy's Agency Decimal File Records, 1928 - 1949 in the Records of the Bureau of Indian Affairs (Record Group 75) that contain the bulk of the records for that agency. There are some records up to 1965 within the Fort Belknap Agency records. For access to these records or copies of the finding aids, please contact the National Archives at Denver (RM-DV) via email at firstname.lastname@example.org
Due to the COVID-19 pandemic and pursuant to guidance received from the Office of Management and Budget (OMB), NARA has adjusted its normal operations to balance the need of completing its mission-critical work while also adhering to the recommended social distancing for the safety of NARA staff. As a result of this re-prioritization of activities, you may experience a delay in receiving an initial acknowledgement as well as a substantive response to your reference request from RM-DV. We apologize for this inconvenience and appreciate your understanding and patience.
Any BIA records still with the agency have been moved to the American Indian Records Repository.
We hope this information is helpful. Best of luck with your research!
[Information provided by Cody White, Subject Matter Expert]