The Wind River Reservation, southwest of Thermopolis, is home to the Eastern Shoshone and Northern Arapaho tribes.

The tribes have a diverse history. The Shoshone, under their great chief Washakie (ca 1843 to 1900), was traditionally allied with the U. S. Army. The Northern Arapaho engaged in a longer period of hostilities with the U. S. forces. Bates Battle was fought on July 4, 1874 between the Arapaho led by Chief Sharpnose, and U. S. troops and their Shoshone allies led by Chief Washakie.

The Arapaho repeatedly requested a Reservation of their own, but were always denied one. Despite the traditional antagonism between the two tribes, the Northern Arapaho were moved to the Wind River Reservation in 1877, which had been the home of Washakie's Shoshone since the 1860s.

Washakie of the Shoshone and Sharpnose of the Arapaho were two of the Native American leaders who participated in negotiations leading to the treaty of 1896, which ceded the area surrounding the Hot Springs State Park to the United States Government. This treaty led directly to the 1897 foundation of Thermopolis.