Guan Lansheng (1st R), director of a research institute in Lanzhou Jiaotong University, stirs the dye vat at the institute in Lanzhou, northwest China's Gansu Province, March 9, 2021. The dyes used in this ancient printing and dyeing technique are all natural. Such technique has been listed as a provincial-level intangible cultural heritage. (Xinhua/Ma Xiping)
