In his book Our Wild Indians, Richard Irving Dodge described hand signs used by Plains Indians to identify other Indians.
The signs described other Indians according to the Plains’ word or words for those Indians. For example, with the “right hand extended to left and front of body, index finger extended, others [fingers] closed, draw the hand backward with a wriggling motion across the body. The motion symbolized the Plains Indian name for Comanche: “snakes.”
Ute – Left hand held horizonally in front of body, fingers extended, thumb closed on palm, edge of hand down. With extended fingers of right hand, rub gently toward the wrist, along the extended index finger of left hand. An alternative was to make the sign for black and the generic sign for Indians to indicate the dark skinned Utes.
Apache – same as left hand position for Ute. With extended fingers of right hand flip back and forth on the index finger of left hand as a barber strops a razor. (meaning unknown to Richard Dodge).
Arapahoe – index finger of right hand extended, rub right side of nose. Origin and meaning unknown.
Kiowa – open palm as though holding a small bowl beside the right side of face, make circular motion. This symbolized the Kiowa style of cutting the hair off the right side of the head.
The Plains Indians had descriptive names for many groups:
Sioux – “cut throat”
Cheyenne – “cut finger”
Pawnee – “wolf”
White man – “hat wearer”
Mexican man – “beard wearer”
Negro man – “black white man”
From: Our Wild Indians: Thirty-three Years of Personal Experience Among the Red Men of the Great West by Richard Irving Dodge, A.D. Worthington and Company, Hartford, CT, 1882, page 390-391.