The Video That Started It All For Me

https://www.youtube.com/watch?v=s1-StAlw3aE

Portrait in the thumbnail of Shoshoni Chief Tendoi Demonstrating Sign Language. (Photo by Charles M. Bell, circa 1880, courtesy National Anthropological Archives, Smithsonian Institution, Washington, D.C.)

Another Video

https://youtu.be/HQ5UoqXMblY?si=HzlZ3CelRET7KOm5

Le Wiki

Plains Indian Sign Language

Books

Talking with Hands: Everything You Need to Start Signing Native American Hand Talk - A Complete Beginner's Guide with over 200 Words and Phrases

Indian Sign Language (Native American)

Sources

North American Plains Sign Language, older than European and Ottoman Sign Languages