"It developed from items of Pueblo clothing, from even more historic Navajo clothing and the wool fiber that the Navajos were so proficient at using. The spinning skills possessed by the weavers in those days were astounding and their access to excellent wool was superior to anything that most of us have today. They would sort the wool from the dual coated to Navajo-Churro sheep, using the finest of it to spin yarn that Armani and Versace would drool over. This yarn would be woven into blankets and clothing that would be used and repaired until it could be used no more. Like today’s biil, these older weavings were simple, often with only one or two bands of patterning in an otherwise plain weave." - Mary Walker
Mary also emphasizes the time it takes to make a biil, as it often takes 12-18 months for a weaver today to create these weavings as they use such fine wool and silk fibers.