Cisalpine Gaul

Cisalpine Gaul was a province of Rome which was separated from Italy-proper by the Rubicon. The province itself was also considered by River Song to be a part of Northern Italy. (PROSE: The Ruby's Curse)

In 44 BCE, Julius Caesar crossed the Rubicon with an army, entering Italy from Cisalpine Gaul. This act broke Roman law and incited a civil war. The Seventh Doctor, and River Song were all present at this event. (COMIC: Crossing the Rubicon, PROSE: The Ruby's Curse)