Yan’an City is located along the middle reaches of the Yellow River. This Loess Plateau was once one of the most ecologically fragile areas in China. In 1997, Yan’an was the first Chinese city to explore the "Returning Farmland to Forest Program." Two decades after the launch of the program, the revenue of the villagers has tripled. The frontline of the green space in Shaanxi Province has pushed over 400km northward.