intercourse
Sparta's declaration of war against Athens began the Peloponnesian war. Sparta accused Athens of breaking their peace and the war began in 431 BCE.
Athens
No, It began in London.
Athens began minting its own coinage.
Athens had the First Republic.
begin
Marathon .
serona
Athens was the birthplace of democracy. When Philip the 2nd conquered Greece, Athens was still making its own laws but was supervised. Eventually their democracy was ended and never really began again.
Persians
It began with Cleisthenes establishing a popular assembly in 508 BCE.
Allies Sparta and Athens had a falling out when the Spartan helots revolted and the forces Athens sent to help Sparta began to side with the revolutionaries, and Sparta sent them home. Athens turned the Delian league it had led against the Persian Empire into an empire of its own, and began to interfere in the cities of the Peloponnesian league led by Athens resulting in open war.