Suffering for the sake of moral strengthening is one important theme that permeates throughout the sweat lodge, Bucko explained in his book.

BBC: The origins of bathhouse culture around the world

The earliest accounts of sweat lodges in Native American culture appear in writings by European settlers from the 1600s, and according to anthropologist Raymond A Bucko, author of The Lakota Ritual of the Sweat Lodge, sweat lodges have not changed significantly since that time.

BBC: The origins of bathhouse culture around the world