This is a contribution from Moko (cleaned up by Pip) of a postcard being sold on Ebay. It not only illustrates how tribal people in remote areas may have less inhibitions about nudity but how photographers from so-called civilized areas might exploit this for monetary gain or fame in the name of scientific ethnography. After all, this did not appear in some text in an academic tome, but put on a postcard that could be disseminated publicly. Nothing is really known about the provenance of this image but the seller claims it is over 100 years old.
To my eye (correct me if I am wrong) these girls are not Han Chinese—the dominant population in China—so the photographer was most likely English but there is a remote chance that he/she was Chinese.
The seller did not specify exactly where in China the photograph was taken. My guess is that the girls are ethnic Miao fron Yunnan or elsewhere in south China. The Miao are less inhibited than the Han Chinese, and traditionally wear very short skirts.
Yes, that is my conjecture as well—probably one of the minority races living the Yunan state in southwestern China. -Ron