ating the same acreage as always, albeit by a more modern method that returned less runoff to go downstream to Montana.  (A subsequent 2011 Supreme Court case, in which Montana asserted ownership of Missouri Basin riverbottoms, so as to collect decades of back rent from a hydropower company, is unrelated. On February 22, 2012, Montana lost that case too.)
The name is widely believed to have been derived from the Minnetaree Indian name Mi tse a-da-zi (Yellow Rock River) ( Hidatsa: miʔciiʔriaashiish').  Common lore states that the name came from the yellow-colored rocks along the Grand Canyon of the Yellowstone, but the Minnetaree never lived along the upper stretches of the Yellowstone. Some scholars think that the river was named after yellow-colored sandstone bluffs on the lower Yellowstone, instead.  The Crow Indians, who lived along the upper Yellowstone in Southern Montana, called it E-chee-dick-karsh-ah-shay (Elk River). Translating the Minnetaree name, French trappers called the river Roche Jaune (Yellow Rock), a name used by mountain men until the mid-19th century. Independently, Lewis and Clark recorded the English translation of Yellow Stone for the river, after encountering the Minnetaree in 1805. With expanding settlement by people from the United States, the English name eventually became the most widely used.  The river was explored in 1806 by William Clark during the return voyage of the Lewis and Clark Expedition. Clark's Fork of the river was named for him.
The Yellowstone River had long been an important artery of transportation for Native Americans. In the 19th century, European-American settlers depended on it as well, entering the region by riverboat. The region around the Big Horn, Powder and Tongue rivers is the traditional summer hunting grounds for numerous Native American tribes: Lakota Sioux, Crow, Cheyenne and Cree. Gold was discovered near Virginia City, Montana in the 1860s, and two of the primary routes for accessing the gold fields were the Bozeman Trail and the Bridger Trail both of which followed the Yellowstone for a short length.
Native American anger at settler intrusion into the hunting grounds led to Red Cloud's War. The conflict was settled with the Treaty of Fort Laramie in 1868, by which the US granted the territory of the Black Hills and the Powder River Country to the Lakota people.  This region included the drainages of the Big Horn, Powder and Tongue rivers. The discovery of gold in 1874 in the Black Hills, however, attracted thousands of miners who invaded the sacred grounds, and conflicts broke out with the Sioux.
The new competition and violence led to the Great Sioux War of 1876-77. The US sent in troops to protect the miners, although they had violated the treaty, and to defeat the Sioux. In 1876, Colonel John Gibbon led a column of men from Fort Ellis near Bozeman, Montana and traveled down the Yellowstone to meet up with General Alfred Terry's Dakota Column, which had traveled upstream from North Dakota. Terry formed a base of operations at the mouth of Rosebud Creek on the Yellowstone, but the US miscalculated the strength of the Lakota who had gathered by the thousands along the river. Lieutenant Colonel George Armstrong Custer departed from Rosebud Creek with the 7th Cavalry on the expedition that ended in his complete defeat by the Lakota and Cheyenne at the Battle of the Little Bighorn. The army ferried its survivors down the Yellowstone to Fort Abraham Lincoln on the Missouri River.
After the US achieved victory the tribes were forced onto reservations. The Sioux and allies were forced from eastern Montana and Wyoming: some bands fled to Canada, while others suffered forced removal to distant reservations, primarily in present-day South Dakota and Nebraska west of the Missouri River. Crow warriors had enlisted as scouts with the US Army during the war and the Crow Indian Reservation was established in south-central Montana. The Northern Cheyenne Indian Reservation is south of the Yellowstone in Montana.
Many of the early expeditions to the area that would later be