In the Greek decline, the war between? and? caused the decline

Spartan oligarchy and Athenian democracy

Explanation:

These city-states were separated by a range of mountains and although they are both Greek, their traditions and ideals greatly differed and they both created their mini-empires. Their war started for no good reason, and with Sparta's victory, Greece had lost its ideals, threw out their most treasured traditions, and exhausted their power. Due to this, it gave the path for Macedonians to conquer it.