The iron gate is located in the Kuruktag Valley, north of Korla City, and is the middle throat of the ancient Silk Road. It is a natural dangerous pass through the traffic in the north and south Xinjiangs, and it is also the dividing line of the north and south Xinjiangs. The Jin Dynasty set up a customs here, because of its insurance, so called "iron gate gate", iron gate gate is listed as one of the 26 ancient customs in China.