A mutually supportive arrangement to ensure stability.
Yes.
The Persian Empire .
The Persian Wars
The Persian king, and first Sparta then Athens on the Greek side.
The Persian Wars 490 to 449 BCE.
Persian Wars
Athens and Sparta were friendly before the Persian War. They naturally joined the alliance which repelled the Persian invasion. A Spartan force helped Athens retain its government against a revolt pre-war. Athens post-war helped Sparta put down a serf rebellion, but then started to side with the serfs, so the Spartans sent them home. That was the split.
The Persian Empire and an alliance of Greek city-states led first by Sparta and then Athens.
The Persian Empire versus a coalition of Greek city-states, at first led by Sparta, then by Athens.
Two leagues - one led by Athens, the other led by Sparta.
There were over 200, led at first by Sparta, then by Athens.
In the first part, Miletus. In the second part Sparta. In the third part, Athens.