trappers found the area in the late 18th century peopled by Native American tribes such as the Blackfoot, Northern Cheyenne, Sioux, Assiniboine, Gros Ventre, Crow, Plains Cree, and Plains Ojibwa. The Lewis and Clark Expedition passed through the Breaks in 1805 and were the first to document the region through notes and drawings, and their sighting and documentation of bighorn sheep in the Breaks region was the first time this species was recorded in North America by white explorers. Much of the Breaks region has remained as it was when Lewis and Clark's party first saw it. The confluence of the Judith and Missouri Rivers was the setting for important peace councils in 1846 and 1855. In 1877, the eastbound Nez Perce crossed the Missouri and entered the Breaks country in their attempt to escape to Canada. The Cow Island Skirmish occurred in the Breaks and was the last encounter prior to the Nez Perce's surrender to the U.S. Army at the Battle of Bear Paw, just north of the monument." carved the Breaks into the Montana landscape
Management and conservation
A full management plan is still under development due to various private inholdings and lease agreements between private citizens and the federal government. While conservationists would like to see some of the Breaks monument lands become designated as Wilderness, local ranchers and farmers under long standing lease agreements with the federal government, who graze upwards of 10,000 head of cattle annually within the new monument, are concerned that the monument status may adversely affect their livelihood and the economies of local towns. Under the proposed management plan from the Department of the Interior, although the resources of the monument will be given better protection, "currently permitted livestock grazing, hunting, fishing, and similar activities will generally not be affected, nor will private property and state land within the boundary of the proposed monument, as well as other valid existing rights." In 2013, the U.S. Court of Appeals ruled that the BLM's management plan violated historic site laws with their practices. The National Trust for Historic Preservation cited the site as one of ten historic sites saved in 2013. The Breaks is home to at least sixty mammal species and hundreds of bird species. Willows and shrubs are found along the Missouri River banks while sagebrush and short grass prairie are dominant elsewhere.