In the 19th century, Native Americans from central Canada to northern Mexico could communicate using Plains Indian Sign Language, a lingua franca that facilitated trading, hunting, storytelling, and warfare between speakers of different languages. It’s estimated that in 1885 more than 110,000 indigenous people were familiar with the signs. Today only a few dozen fluent signers remain, though efforts are afoot to preserve the language.

Above: In September 1930, U.S. Army general Hugh L. Scott attended the Indian Sign Language Grand Council, an intertribal gathering of indigenous leaders convened to document and preserve PISL.