Rangers patrol at a shelterbelt forest in Shannan, southwest China's Tibet Autonomous Region, July 23, 2018. Over the past four decades, the Shannan people have made achievements in desert control by building a 1.8-kilometer-wide "green Great Wall" that stretches 160 kilometers. More than 30,000 hectares of desert land in the middle reaches of Yarlung Zangbo River has been reclaimed. (Xinhua/Liu Dongjun)