Gansu is located in the northwest of China. The Yellow River passes through Lanzhou, dividing this land into Hedong and Hexi. Mountains in the south and north squeeze out a narrow corridor of about 1,000 kilometers, with oases connecting the Central Plains and the Great Wall. Our flight journey started from central Gansu and encountered a different kind of Loess Plateau. Travel through the time and space tunnel, overlooking the past and present of farming civilization, go down the river to see how a large river changes colors, and finally encounter an ancient city unexpectedly.