Roman Empire

The Roman Empire is an enormous empire based in the city of Rome. It is known as being one of the world's largest empire. The Romans are prone to calling anyone outside of their empire "barbarians" such as the Vikings. They had a conflict with Hiccup Horrendous Haddock III and the Hairy Hooligan and Bog-Burgar tribes in How to Speak Dragonese.

Trivia

 * In real life, the Romans and the Vikings could have never actually encountered each other as the Roman Empire fell around 300 years prior to the first Viking raid. Cressida Cowell actually acknowledged this on her website, stating that the How to Train Your Dragon book series is "fiction pretending to be history."