The Roman Empire.
( What has gone before. )
770 BCE. A wolf suckles two twin babies instead of just eating them !
753 BCE. The Twins grow up, Romulus kills Remus and then builds a city to hide the body !
( By the way this is what passes for history back then. )
509 BCE. Romans kick out the Etruscan King and become a Republic.
400 BCE. Rome is sacked by the Celts.
55 + 54 BCE. Caesar invades Britannia, The locals watch with amusement when he goes away again.
27 BCE. Octavian kicks out the Republicans and makes himself Emperor.
43 CE. Claudius invaded Britannia properly.
61 CE. Romans seriously under estimate the fury of a woman scorned.
122 CE. Hadrian builds a wall to neaten up the border a bit near Scotland.
( For more details and less flippancy see the Chronology. )