island that became romes northwester frontier

The island that became Rome's northwestern frontier is Britannia, which is modern-day Great Britain.

To find this answer, you can follow these steps:

1. Start by understanding that Rome was an ancient civilization with a vast empire that encompassed much of Europe, northern Africa, and parts of the Middle East.
2. Next, consider Rome's geographical location and the regions it controlled during its peak.
3. Identify the part of the empire that lies to the northwest of Rome. From a map, it is evident that the British Isles, specifically Great Britain, fit this description.
4. Once you have determined that Britannia is the likely answer, verify it by cross-referencing historical sources such as books, scholarly articles, or online history databases.
5. Consult reputable sources that discuss Rome's expansion and conquests to confirm that Britannia served as Rome's northwestern frontier. These sources may include academic publications, historical accounts, or lectures from experts in the field of ancient history.

By following these steps, you can confidently conclude that Britannia became Rome's northwestern frontier.