Jerga is a very old part of our tradition, dating back to the Spanish Colonial era. It is a simple twill weave, either a straight twill or a diamond twill called ojo de perdiz. Historically, this was the utilitarian fabric of New Mexico, used to wrap up bundles as you might use a tarp, or on the floor if you were really wealthy. Since most of what we weave uses only two harnesses on our looms, and this uses four harnesses, it is rarely woven by weavers in our tradition, who don't usually have appropriate looms.
For more information on the history of jerga in New Mexico see Jerga.