Amid snow-capped mountains and deep valleys in Angsai Township of Zaduo County, an area in Sanjiangyuan National Park, Tseten and Kunga trek over ridges, cross alpine meadows and carry out ecological patrols, pressing the shutter as they move through the landscape. In 2016, Tseten and Kunga became rangers under a public welfare program. Having taught themselves photography, they have been documenting the mountains, rivers and wildlife of their homeland with their cameras while patrolling, collecting litter, monitoring water sources and observing vegetation. Over a decade, their footprints have spread across the grasslands and river shores. Their lens have remained fixed on the changes unfolding on this land: wildlife populations are increasing, traces of garbage on the grasslands have largely disappeared, and the ecological landscape along the Lancang River has grown better and better.