This is a first-phase Navajo chief's blanket, circa 1840. These blankets were woven by the Navajo and traded to with other populations. When draped around the shoulders the stripes match up in front of the body. A blanket that's been worn, like this one in the DMNS collection, has areas of stretching where the wearer gripped it closed. The oldest and rarest style, only about 50 first-phase blankets are known to exist today.