The Mark of the Thief is set in third-century Rome during the reign of Emperor Tacitus. It is believed that he was born sometime around 200 and ruled from late 275-276, during a period of internal and external instability. Tacitus’s rule ended with his death, but the cause is uncertain. It is believed that Tacitus died either from disease or at the hands of his own soldiers, a detail the novel incorporates at the end when Radulf informs Nic that the emperor is likely already dead, implying that he died at the hands of soldiers loyal to Radulf. The historian Tacitus was succeeded by a half-brother, Florian, whose rule lasted three months before his soldiers assassinated him.

Tacitus and Florian’s brief rules exemplify the volatility of the third-century Roman Empire, which was beset by economic problems, invasions, political turmoil, and civil wars. This state, however, is not entirely unique in Roman history, as it has a long series of bloody wars, both civil and external. The Mark of the Thief remarks on this when Felix recounts the myth of Remus and Romulus in Chapter 12: One of Rome’s foundation myths characterizes it as originating in a war between brothers.