Nankow pass, Pechili province, China. Photograph by John Thomson, 1871.

A river running through a pass between mountains, with a man and a donkey standing in the foreground. Nankou Pass, or the southern entry, is situated in Changping county in a suburb of Beijing. Sandwiched between two high mountains, it has been of strategic importance throughout history. From here one can see the first spur of the Great Wall. The Pass is very rocky and rough, and for centuries donkeys were the beasts of burden used by traders for transporting goods through and beyond the Pass.

Nankow pass, North China, leading to the Great Wall. Bears Thomson's negative number: "509"