The Roman Empire plays a large role in How to Train Your Dragon Book 3, How to Speak Dragonese . During the time of Tiberius Caesar, Rome is gradually growing very large indeed, and its conquests have brought it to the Archipeligo. A legion of Roman soldiers has arrived sailing towards Berk as Hiccup engages in a fishing lesson, and is shown to be carrying kidnapped dragons. These dragons are all part of the master plan of the Thin Prefect, a Viking man who is building an army in order to steal the undersea treasure of the Calliban Caves. Eventually, though, along with Fishlegs and Camicazi, Hiccup foils their plan, and the Roman Empire is not seen afterward.