History of Montana degree of longitude northward to the boundary line of the British possessions. The boundaries of Montana territory did not change during its existence. Montana was admitted to the Union as the state of Montana on November 8, 1889. The Battle of the Little Bighorn—also called Custer's Last Stand and the Battle of the Greasy Grass—was an armed engagement between a Lakota (Sioux)-Northern Cheyenne-Arapaho combined force and the 7th Cavalry of the United States Army. It occurred June 25–June 26, 1876, near the Little Bighorn River in eastern Montana Territory near present-day Hardin, Montana, on land that today is part of
Little Bighorn River Sheep river. The trappers who came to the Big Horn Mountains in the fur trapping era continued the usage of the English translation of the Indian names, and the names for both rivers have come down through history. Captain Reynolds had Jim Bridger as a guide and interpreter, so the information about the source of the name was confirmed by Reynolds from Indian sources through Bridger. According to the USGS, the Little Bighorn River has three other official variants of the name, including Little Horn River, Custer River and Great Horn River. Local people who live in the valley and