Sandstorms are a reminder of the power of nature for the residents of Dunhuang, the Chinese oasis town at the edge of the Taklamakan and Gobi deserts, as they have been for their forebears for centuries.

Liu Hongwen, 56, recalled numerous instances when visibility was so bad he could not tell who was standing right next to him. One time many years ago, he thought he was lost on his way from primary school only to discover he was right at the back of his house after the storm had passed. The same sandstorms were recorded in the Book of Han in the Han dynasty around 80BC, which described the relentless “strong wind blowing from the northwest, turning clouds yellow”.