About 顓渠 Chwangü
The widespread legend on the Internet that Chwangü (which came from 顓渠 in the Chinese records) was a Chinese princess is ill-founded. In fact, Chwangü was not a name of one individual, but more likely a title for the principal wife of Chanyu. The confusion was furthered by the nomadic practice that the widows of a deceased man were taken by his son or brother, thus the many occurrences of 顓渠 were taken to be a single, rather prominent female.
A good English account is A Thousand Years of the Tartars by Edward Harper Parker (1895)