Ancient authors were usually held to a higher standard of credibility if they were reporting recent events. But authors who were writing about distant events were just like modern screen writers making historical epics. They were expected to included exciting events, themes, certain types of characters, etc. Dionysus of Halicarnassus, for example, wrote about the early history of the Roman Empire (in some cases thousands of years before his own time), and included direct quotes of intimate conversations.