Archaeologists working in the Northwestern Plains and the northern Rocky Mountains have generally been unable to tie prehistoric archeological sites in Yellowstone to recognized historic tribes. However, the best identification appears to be for the Shoshone who may have come from the Great Basin to the intermountain area of Wyoming and Montana as early as A.D. 1,200.
In the 19th century, the earliest EuroAmerican expeditions to Yellowstone recorded that the Sheepeaters (a band of the Shoshone) were the only year-round residents in what became Yellowstone National Park. The Sheepeaters made their living hunting mountain sheep and were well known for the high quality bows they made from mountain sheep horn. By soaking the horn in the park’s hot waters, the Sheepeaters straightened the horn during the bow-manufacturing process. Some of the park’s early historic wickiups (wooden shelters) were undoubtedly made by these people. Today it is known that many other tribes were drawn to Yellowstone during the warmer months by the rich hunting, fishing, and stone sources for tools.
We are able to identify prehistoric peoples who visited Yellowstone because of the obsidian tools found at archeological sites around the country. Obsidian has trace elements in it that make each source of obsidian chemically unique, just like human fingerprints are unique for individuals. This uniqueness permits identification of the geological source for obsidian artifacts. Yellowstone has several obsidian sources, and tools made from Yellowstone obsidian have been found as far away as Ohio. Conversely, some obsidian tools found in the park are made from obsidian from Idaho and southwestern Montana,
thus leading to the conclusion that these tools were brought into Yellowstone by prehistoric peoples who lived part of the year elsewhere.
Systematic investigations into the archeological record of the area have taken place only in the past few years, but preliminary results show the area that is now included in Yellowstone National Park has attracted people, at least seasonally, to its rich plant and animal resources for thousands of years.