Titles of Chinese rulers.
I got curious about this question from a series of novels, but since it's a factual-historical question I thought it would fit better in GQ than Cafe Society.
British author David Wingrove has written a series of eight science-fiction novels (I've read the first seven) called "Chung Kuo," set in a future in which traditional, Confucian Chinese civilization has re-emerged and conquered the entire world. The world is divided into seven regions called "cities" (and each is a city, a 100-storey arcology covering the bulk of a continent). Each city is ruled by a hereditary "t'ang," who is surrounded with what appear to be the ancient, traditional trappings of Chinese monarchy.
So, my question is, what is a "t'ang"? Wingrove defined a lot of Mandarin terms in back-of-the-book glossaries, but not this one. I would assume it means emperor. But I'm pretty sure that in Mandarin, "huang ti" means emperor, and "wang" means king or duke. So what is a "t'ang"?
Also, does anyone happen to know: I've read that the title "huang ti" (which can be translated loosely as "august sovereign" or "divine autocrat") was invented by the First Emperor, King Cheng of Ch'in. Is that true? Was it never in use before his time? What titles were used earlier, by the legendary Yellow Emperor, Yao and Shun, and the Hsia, Shang and Zhou rulers?