The Shoshone can be divided into three different groups: the Northern Shoshone, who were largely concentrated in Idaho, Utah, and Wyoming; the Western Shoshone, who lived primarily in Oregon and Idaho; and the Eastern Shoshone, mainly found in Wyoming, Colorado, and Montana. Each group ranged quite a bit from where they lived, and members of each group passed through Montana in its early history.
The Western and Eastern Shoshone adopted horses early, and utilized them to their fullest. They moved out of the mountains and onto the plains, and adopted many of the traits associated with the Plains Indians, such as hunting buffalo, using tipis, and raiding other tribes for horses. The Northern Shoshone preferred to only use the horse as a draft animal, and they didn’t become fully mounted until the mid-19th century.
Still, the Shoshone’s push east onto the plains didn’t last long, for by 1750 the Blackfeet had arrived, pushed west by the Europeans, and they drove the Shoshone back. The Shoshone were no match for the Blackfeet, for they had no guns to match those the Blackfeet had gotten from the Europeans.
To add insult to injury, a smallpox epidemic struck in both 1781 and 1800. These double intrusions, of Blackfeet and smallpox, reduced the Shoshone numbers so much that by the time Lewis and Clark came through the state, they had no permanent presence, and did little more than scout in single-person or small groups.
A year later, when she was about 13 years old, she was married to Toussaint Charbonneau, a fur trapper native to Quebec. Toussaint already had another Shoshone wife, a young girl named Otter Woman, and it’s still unclear whether he purchased the girls, or won them gambling.
Either way, it was while he was living in North Dakota that the Lewis and Clark expedition pulled in to stop for the winter, building Fort Mandan as a winter base. They needed skilled interpreters, but they found Toussaint’s language skills inadequate. But when they learned that he had two Shoshone wives, they hired him right away, and Montana has never been the same since.
Murphy, Robert F. and Yolanda Murphy. "Northern Shoshone and Bannock." Warren L. D'Azevedo, vol. ed. Handbook of North American Indians, Volume 11: Great Basin. Washington, DC: Smithsonian Institution, 1986. p 285-306.
Pritzer, Barry. Native Americans [2 Volumes]: An Encyclopedia of History, Culture, and Peoples. ABC-CLIO: Santa Barbara, 1998. p 236-7.
Stamm, Henry E., IV. The People of the Wind River: The Eastern Shoshone, 1825-1900. The University of Oklahoma Press: Norman, 1999. p 3-8.