Traditional Oriental rugs are made on vertical looms strung with 3 to 24 vertical warp threads per centimetre. Working from bottom to top, the rug maker either weaves the rug for a flat surface or knots it to form a pile. After the rug is completely knotted, its pile is sheared and the warp threads at each end are tied off to form a fringe. the finer the yarn and the closer the warp threads are together, the finer the quality of the rug. Valuable, fine-textured rugs have 400 or more knots per square inch (62 per square centimetre); coarse rugs may have less than 50 knots per square inch (8 per square centimetre).
Traditional nomad rugs usually use wool for both the warp (vertical thread) and weft (horizontal thread). These rugs are likely to give a little with use; they may slant or go bumpy. Workshop rugs most commonly have a cotton warp as a foundation.
The colours used in oriental rugs often have special significance but this varies from place to place. For example, green is the colour of the Prophet and rarely used other than in prayer rugs in Moslem countries; in China, Iran and India, white symbolises grief; in China, yellow is the Emperor’s colour but in Moslem countries it represents piety; in Mongolia, blue represents authority and red represents wealth or joy.