Plains Indian Sign Language (PISL), also known as Hand Talk or Plains Sign Language, is an endangered language common to various Plains Nations across what is now central Canada, the central and western United States and northern Mexico. This sign language was used historically as a lingua franca, notably for trading among tribes; it is still used for story-telling, oratory, various ceremonies, and by deaf people for ordinary daily use.

The Arapaho are a Native American people historically living on the plains of Colorado and Wyoming. They were close allies of the Cheyenne tribe and loosely aligned with the Lakota and Dakota.