The distance between Seonyeong, the capital of Qinghai, and Lanzhou, the capital of Gansu, is a mere four hundred li—only four hundred li! For the people of the Central Plains, masters of walking (as are people of every era, to be honest), it’s practically right next door. However, the elevation difference is striking, with Seonyeong sitting on a high plateau about 250 jang above Lanzhou. By Cheong’s standards, that’s the equivalent of a 300-story building.

In other words, the path to Lanzhou was a 300-story descent. While the reverse, the uphill journey to Seonyeong, would be grueling even for seasoned …