Isfahan has long been one of the centers for production of the famous Persian Rug. Weaving in Isfahan flourished in the Safavid era. But when the Afghans invaded Iran, ending the Safavid dynasty, the craft also became stagnant. Not until 1920s, between two world wars, was weaving again taken seriously by the people of Isfahan. They started to weave Safavid designs and once again became one of the most important nexus of the Iranian rug weaving industry. Isfahani carpets today are among the most wanted in world markets, having many customers in western countries. Isfahani rugs and carpets usually have ivory backgrounds with blue, rose, and indigo motifs. Rugs and carpets often have very symmetrical and balanced designs. They usually have a single medallion that is surrounded with vines and palmettos and are of excellent quality. These carpets are often made up of pure silk. A combination of silk and wool is also sometimes found. These materials make up the pile of the rugs, while cotton is usually used to hand knot a strong and durable foundation. In finer Isfahans, silk is used as a base.