At one point in history, the various tribes in the Plains region developed a shared universal language. But it didn't rely on the spoken word. Plains Indian Sign Language (PISL), or Hand Talk, was a complex means of communication that spread over a large swatch of North America. It was a way for deaf people to communicate before the invention of American Sign Language (ASL). Colonial intrusion and assimilation policies caused the number of PISL practitioners to drop off drastically. Now, a handful of PISL speakers are trying to revitalize this unique language.