Final answer:
The Persian invasions in the 5th century BCE united the Greek city-states, such as Athens and Sparta, against a common enemy and fostered a sense of unity and identity among the Greeks.
Step-by-step explanation:
The Persian invasions united the city-states into a "Greek" mindset in the 5th century BCE. The Greek city-states, including Athens and Sparta, were faced with a common enemy and joined forces to repel the Persian invaders. The shared experience of defending their homeland against a powerful external threat fostered a sense of unity and identity among the Greeks.
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