Known for their brutal training regime, the Agoge, a militaristic society, male children were separated into the weak and strong. At the age of seven, the strong were sent off to begin their military training. The weak were sent to the mountains, to die. Sparta was also known for their great, long lasting rivalry with the city-state of Athens. Sparta fought many wars, battling many foes, such as the Persians, Athenians, and other Greek city states. Neither Philip II of Macedonia nor Alexander the Great tried to conquer Sparta, and so the Spartans were the only Greeks who didn't take part in Alexander's war against Persia.