In almost all Quechua ethnic groups, many traditional handicrafts are an important aspect of material culture. This includes a tradition of weaving handed down from Inca times or earlier, using cotton, wool (from llamas, alpacas, guanacos, vicunas) and a multitude of natural dyes, and incorporating numerous woven patterns ("pallay"). Houses are usually constructed using air-dried clay bricks ("tika", or in Spanish "adobe"), or branches and clay mortar (“wattle and daub”), with the roofs being covered with straw, reeds, or puna grass ("ichu").