This was part of a development called Ledger Art, named for the accountants' ledger books used by Native Americans for their drawings and paintings. It was particularly associated with the art produced in the late nineteenth century by Native American men held at Fort Marion in Florida. They were held for more than a decade as prisoners of war, or political prisoners, following the Plains Wars. In addition to classes in English and other topics of United States society, the fort's officials provided the men with drawing materials and ledger books for their work. The collection of ledger books is held by the Smithsonian Institution.