“Portentous talk” (yāoyán), like disseminated talk and unverifiable talk, was a common speech tag in traditional Chinese political and social life. Compared with the latter two, portentous talk was especially loathed by rulers throughout the ages. In the course of more than 2,000 years, successive governments had done quite a good job of stigmatizing portentous talk. To most scholar-officials and the general public, portentous talk represented negative information that was grotesque, macabre, dangerous, and untrustworthy. In Modern Standard Chinese, disseminated talk and unverifiable talk are defined as falsities, fallacies, absurdities, and superstitions; hearsay that is not based on facts; information that is fabricated, which can be readily used by persons with ulterior motives to mislead and fool the people. Even as disseminated talk and unverifiable talk are seen as “rumors,” portentous talk is defined as “heresy that baffles,”1 “exceedingly strange heresy,”2 “nonsense, lies,” and “heresy, talk that confuses people’s hearts.”3 Portentous talk is also a manifestation of rumor. This chapter attempts to acquire a fuller and deeper understanding of portentous talk during the early imperial period, as well as the political and social roles it played, by examining and interpreting the occurrences and contexts of portentous talk in historical texts.