The latest event Diodorus mentions is Octavian's vengeance on the city of Tauromenium, whose refusal to help him led to Octavian's naval defeat nearby in 36 BC (16.7). Diodorus shows no knowledge that Egypt became a Roman province—which transpired in 30 BC—so presumably he published his completed work before that event. Diodorus asserts that he devoted thirty years to the composition of his history, and that he undertook a number of dangerous journeys through Europe and Asia in prosecution of his historical researches.