A few centuries back, almost all Turkmen rugs were produced by nomadic tribes almost entirely with locally-obtained materials, wool from the herds and vegetable dyes or other natural dyes from the land. They used geometrical designs that varied from tribe to tribe; most famous are the Yomut, Ersari, Saryk, Salor and Tekke. Irregularities — considered part of the charm by many rug collectors — were fairly common since natural materials vary from batch to batch and woolen warp or weft may stretch, especially on a loom that is regularly folded up for transport and set up anew at another camp.