Written records establish the Navajo as fine weavers for at least the last 300 years, beginning with Spanish colonial descriptions of the early 18th century. By 1812, Pedro Piño called the Navajo the best weavers in the province. Few remnants of 18th-century Navajo weaving survive; the most important surviving examples of early Navajo weaving come from Massacre Cave at Canyon de Chelly, Arizona. In 1804, a group of Navajo were shot and killed there, where they were seeking refuge from Spanish soldiers. For a hundred years the cave remained untouched due to Navajo taboos until a local trader named Sam Day entered it and retrieved the textiles. Day separated the collection and sold it to various museums. The majority of Massacre Cave blankets feature plain stripes, yet some exhibit the terraces and diamonds characteristic of later Navajo weaving  (wikipedia)