How did the Persians and Greeks interact?

Answer 1

Generally they were in opposition and sometimes at war.

At times some of the Greek city-states were allies of Persia. At other times Persia ruled large numbers of Greek cities and tried to keep them peaceful with mixed success.

Answer 2

Some city-states went over to the Persian side, others banded together to resist it, combining their armies and navies to match the power of Persia and its Greek allies.