Who subjugated Keltica (the region of France)?

The region known as Keltica, primarily inhabited by Celtic tribes, was subjugated by Rome during its expansion across Europe. The process of Roman conquest began in the 1st century BCE, culminating in the establishment of the province of Gallia. The Romans, led by figures such as Julius Caesar, engaged in a series of military campaigns known as the Gallic Wars, which ultimately led to the defeat of significant Gallic leaders like Vercingetorix.

The Romans implemented their governance, culture, and infrastructure in the region, transforming it significantly through urbanization and the spread of Roman laws and customs. This incorporation into the Roman Empire played a crucial role in shaping what would later become France, influencing its language, culture, and societal norms.

The other options listed, while notable in various historical contexts, did not participate in the subjugation of Keltica. The Ottoman and Persian Empires expanded in different regions and focused on areas outside of Western Europe, while Germany's historical interactions and influence developed in later centuries and did not involve the direct subjugation of the Celtic tribes in Keltica. Thus, Rome is the correct answer due to its decisive military and cultural impact on the region during the ancient period.