A villager collects salt at a saline field in Mangkam County, southwest China's Tibet Autonomous Region, May 22, 2019. An ancient technique of salt production since Tang Dynasty (618-907) is well-preserved in Mangkam County. Local people follow a salt harvesting method by collecting brines from salt mines and ponds and evaporating them in the sun until crystallization. (Xinhua/Li Xin)