Originally posted by suntze:
Do you have any info why northerners usually refer to themselves as
Han ren and the southerners, ie Cantonese and Hokkiens, as Tang
ren?
No problem. Glad to help a fellow enthusiast in Chinese history.

For the uninitiated, the reason why the Chinese race usually refer
to themselves as descendants of "Han" or "Tang" was because the Han
and Tang Dynasties were two of the most glorious periods in Chinese
history when the country of the Central Plains or China was strong,
powerful, abundant, and vibrant with culture.
"Nan Tang Bei Han"... If my memory served me right, this
distinction originated during the dying years of the Tang Dynasty
when the northern region of China was actually divided among
several autonomous tribe nations like Liao, Xixia and Jin. (Readers
of Jin Yong's pugilistic novels should be familiar with these tribe
nations.)
One remarkable characteristic of the Chinese culture was that the
roots were so deep and the values were so strong that the culture
was able to exercise considerable amount of influence on the
foreign tribal nations that occupied the land. These nations took
to the Han language, rites and government structure naturally
during their occupation of the northern regions, and the citizens
there referred to themselves as "Han ren (citizens)".
On the other hand, most citizens claiming Han roots (though
actually the Han bloodline had already been pretty much corrupted
by that time) moved with the capital to the south, and called
themselves "Tang ren (citizens)" to differentiate themselves from
the Han citizens of the tribe nations up north. Hence the
distinction was born, but it has slowly been blurred as the
centuries rolled by through the subsequent dynasties.
An interesting point of noteworthy mention is that many southern
citizens, especially those in the Guangdong and Fujian provinces,
still retain the tradition of calling themselves "Tang ren". At the
end of the Qing Dynasty when many of these citizens emigrated to
foreign countries and established communal enclaves there, they
named these Chinatown enclaves as "Tang ren jie (street)" or "Tang
cheng (city)".
Anyway, not sure if this information was what you had in mind, and
I can't remember the source to verify the accuracy (and cover my
own ass). But you may wish to refer to this article on Han origins
published on Zaobao online forum last October (it does not talk
much on the distinction between Tang and Han, but there was some
cursory mention in there):
http://www.zaobao.com/special/china/general/letter161004a.html
Feel free to PM me if you wish to discuss anything else on Chinese
history. 