The third least common: 'The mountain' (in Chinese, pronounced "Asia").
According to Yuan Yida , this surname has been found in the town of Guo Yang, and also in the Anhui Province, Xian, and the Zhangwu County of the Liaoning Province. Altogether, there are roughly 2000 people with this surname.
These people didn't know each other but all know the origin of their surname. They described themselves as direct line descendants of Yue Fei, and came to these places because people with the name "Qin Gui" had been persecuted in the past. To change this name, the character "Yue" was turned upside down, thus forming this new surname.
The team helped to unite some of the people sharing this surname, and verified that what they had told them about their lineage was indeed true.
The second least common: "Death".
The surname "Death" is mainly found in the North-West of China, and was taken from
the name of the national minority, which shared this four-figure name during the Northern Wei Dynasty time. At present the number of people with this surname is few, and getting fewer.
The least common surname: "Difficult" (read with a falling tone.)
This one is found in the Henan Province, and originates from the surnames of the Xianbei Nationality in the time of the Southern and Northern Dynasties. Originally it was the name of a bird, and at that time people admired birds greatly, so they used this word "Difficultly" as a surname. Later some of these people moved north to Mongolia, and some moved to the Korean Peninsula, but few stayed in China.